diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 000000000..f93002ab0
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,30 @@
+# EditorConfig is awesome: http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{css,js,py}]
+charset = utf-8
+indent_style = space
+indent_size = 4
+
+[Makefile]
+indent_style = tab
+
+[{.travis.yml,codecov.yml}]
+indent_style = space
+indent_size = 2
+
+# Ignore paths
+[/modoboa/bower_components/**]
+charset = none
+end_of_line = none
+insert_final_newline = none
+trim_trailing_whitespace = none
+indent_style = none
+indent_size = none
diff --git a/.gitignore b/.gitignore
index 7b725b7a5..429e9f678 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,7 @@ DEV
 .ropeproject
 modoboa.iml
 .tox
+.eggs/
 modoboa_test
 .coverage
 build/
diff --git a/.travis.yml b/.travis.yml
index f4cc7f849..887e7d961 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -37,6 +37,8 @@ install:
   - pip install -r requirements.txt
   - pip install -r ldap-requirements.txt
   - pip install -r test-requirements.txt
+  - if [ $DB = POSTGRESQL ]; then pip install -r postgresql-requirements.txt ; fi
+  - if [ $DB = MYSQL ]; then pip install -r mysql-requirements.txt ; fi
   - python setup.py develop
 
 before_script:
diff --git a/README.rst b/README.rst
index ec5c774a8..bd6bdde52 100644
--- a/README.rst
+++ b/README.rst
@@ -30,11 +30,11 @@ Main features
 * Reputation protection: `DNSBL <https://en.wikipedia.org/wiki/DNSBL>`_ checks, `DMARC <https://dmarc.org/>`_ `reports <https://github.com/modoboa/modoboa-dmarc>`_ and more
 * `Amavis <http://www.amavis.org>`_ `frontend <https://github.com/modoboa/modoboa-amavis>`_
 * `Webmail <https://github.com/modoboa/modoboa-webmail>`_
+* `Calendar <https://github.com/modoboa/modoboa-radicale>`_
 * `Address book <https://github.com/modoboa/modoboa-contacts>`_
 * `Per-user Sieve filters <https://github.com/modoboa/modoboa-sievefilters>`_
 * `Autoreply messages for Postfix <https://github.com/modoboa/modoboa-postfix-autoreply>`_
 * `Graphical statistics about email traffic <https://github.com/modoboa/modoboa-stats>`_
-* `Radicale <http://radicale.org/>`_ `management frontend <https://github.com/modoboa/modoboa-radicale>`_
 
 *************
 Documentation
diff --git a/bin/modoboa-admin.py b/bin/modoboa-admin.py
index a637e52c6..78de64d39 100644
--- a/bin/modoboa-admin.py
+++ b/bin/modoboa-admin.py
@@ -7,4 +7,3 @@ from modoboa.core.commands import handle_command_line
 
 if __name__ == "__main__":
     handle_command_line()
-
diff --git a/doc/conf.py b/doc/conf.py
index 37b46b5e5..4f11df49a 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -11,82 +11,86 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
-import sys, os
+from __future__ import unicode_literals
+
+import os
+
+# import sys
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
-#sys.path.insert(0, os.path.abspath('.'))
+# sys.path.insert(0, os.path.abspath('.'))
 
 # -- General configuration -----------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-#needs_sphinx = '1.0'
+# needs_sphinx = '1.0'
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [
-    'sphinx.ext.intersphinx',
+    "sphinx.ext.intersphinx",
 ]
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['.templates']
+templates_path = [".templates"]
 
 # The suffix of source filenames.
-source_suffix = '.rst'
+source_suffix = ".rst"
 
 # The encoding of source files.
-#source_encoding = 'utf-8-sig'
+# source_encoding = 'utf-8-sig'
 
 # The master toctree document.
-master_doc = 'index'
+master_doc = "index"
 
 # General information about the project.
-project = u'Modoboa'
-copyright = u'2018, Antoine Nguyen'
+project = "Modoboa"
+copyright = "2018, Antoine Nguyen"  # NOQA:A001
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 # The short X.Y version.
-version = '1.10'
+version = "1.10"
 # The full version, including alpha/beta/rc tags.
-release = '1.10.0'
+release = "1.10.0"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
-#language = None
+# language = None
 
 # There are two options for replacing |today|: either, you set today to some
 # non-false value, then it is used:
-#today = ''
+# today = ''
 # Else, today_fmt is used as the format for a strftime call.
-#today_fmt = '%B %d, %Y'
+# today_fmt = '%B %d, %Y'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['.build']
+exclude_patterns = [".build"]
 
 # The reST default role (used for this markup: `text`) to use for all documents.
-#default_role = None
+# default_role = None
 
 # If true, '()' will be appended to :func: etc. cross-reference text.
-#add_function_parentheses = True
+# add_function_parentheses = True
 
 # If true, the current module name will be prepended to all description
 # unit titles (such as .. function::).
-#add_module_names = True
+# add_module_names = True
 
 # If true, sectionauthor and moduleauthor directives will be shown in the
 # output. They are ignored by default.
-#show_authors = False
+# show_authors = False
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = "sphinx"
 
 # A list of ignored prefixes for module index sorting.
-#modindex_common_prefix = []
+# modindex_common_prefix = []
 
 
 # -- Options for HTML output ---------------------------------------------------
@@ -94,123 +98,123 @@ pygments_style = 'sphinx'
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 
-on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
+on_rtd = os.environ.get("READTHEDOCS", None) == "True"
 if on_rtd:
-    html_theme = 'default'
+    html_theme = "default"
 else:
-    html_theme = 'nature'
+    html_theme = "nature"
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
 # documentation.
-#html_theme_options = {}
+# html_theme_options = {}
 
 # Add any paths that contain custom themes here, relative to this directory.
-#html_theme_path = []
+# html_theme_path = []
 
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
-#html_title = None
+# html_title = None
 
 # A shorter title for the navigation bar.  Default is the same as html_title.
-#html_short_title = None
+# html_short_title = None
 
 # The name of an image file (relative to this directory) to place at the top
 # of the sidebar.
-#html_logo = None
+# html_logo = None
 
 # The name of an image file (within the static path) to use as favicon of the
 # docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
 # pixels large.
-#html_favicon = None
+# html_favicon = None
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
+html_static_path = ["_static"]
 
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
-#html_last_updated_fmt = '%b %d, %Y'
+# html_last_updated_fmt = '%b %d, %Y'
 
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.
-#html_use_smartypants = True
+# html_use_smartypants = True
 
 # Custom sidebar templates, maps document names to template names.
-#html_sidebars = {}
+# html_sidebars = {}
 
 # Additional templates that should be rendered to pages, maps page names to
 # template names.
-#html_additional_pages = {}
+# html_additional_pages = {}
 
 # If false, no module index is generated.
-#html_domain_indices = True
+# html_domain_indices = True
 
 # If false, no index is generated.
-#html_use_index = True
+# html_use_index = True
 
 # If true, the index is split into individual pages for each letter.
-#html_split_index = False
+# html_split_index = False
 
 # If true, links to the reST sources are added to the pages.
-#html_show_sourcelink = True
+# html_show_sourcelink = True
 
 # If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
-#html_show_sphinx = True
+# html_show_sphinx = True
 
 # If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
-#html_show_copyright = True
+# html_show_copyright = True
 
 # If true, an OpenSearch description file will be output, and all pages will
 # contain a <link> tag referring to it.  The value of this option must be the
 # base URL from which the finished HTML is served.
-#html_use_opensearch = ''
+# html_use_opensearch = ''
 
 # This is the file name suffix for HTML files (e.g. ".xhtml").
-#html_file_suffix = None
+# html_file_suffix = None
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'Modoboadoc'
+htmlhelp_basename = "Modoboadoc"
 
 
 # -- Options for LaTeX output --------------------------------------------------
 
 # The paper size ('letter' or 'a4').
-#latex_paper_size = 'letter'
+# latex_paper_size = 'letter'
 
 # The font size ('10pt', '11pt' or '12pt').
-#latex_font_size = '10pt'
+# latex_font_size = '10pt'
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass [howto/manual]).
 latex_documents = [
-  ('index', 'Modoboa.tex', u'Modoboa Documentation',
-   u'Antoine Nguyen', 'manual'),
+    ("index", "Modoboa.tex", "Modoboa Documentation",
+     "Antoine Nguyen", "manual"),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
 # the title page.
-#latex_logo = None
+# latex_logo = None
 
 # For "manual" documents, if this is true, then toplevel headings are parts,
 # not chapters.
-#latex_use_parts = False
+# latex_use_parts = False
 
 # If true, show page references after internal links.
-#latex_show_pagerefs = False
+# latex_show_pagerefs = False
 
 # If true, show URL addresses after external links.
-#latex_show_urls = False
+# latex_show_urls = False
 
 # Additional stuff for the LaTeX preamble.
-#latex_preamble = ''
+# latex_preamble = ''
 
 # Documents to append as an appendix to all manuals.
-#latex_appendices = []
+# latex_appendices = []
 
 # If false, no module index is generated.
-#latex_domain_indices = True
+# latex_domain_indices = True
 
 
 # -- Options for manual page output --------------------------------------------
@@ -218,10 +222,10 @@ latex_documents = [
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
 man_pages = [
-    ('index', 'modoboa', u'Modoboa Documentation',
-     [u'Antoine Nguyen'], 1)
+    ("index", "modoboa", "Modoboa Documentation",
+     ["Antoine Nguyen"], 1)
 ]
 
 intersphinx_mapping = {
-    'amavis': ('http://modoboa-amavis.readthedocs.org/en/latest/', None)
+    "amavis": ("http://modoboa-amavis.readthedocs.org/en/latest/", None)
 }
diff --git a/doc/configuration.rst b/doc/configuration.rst
index 628261179..996c52559 100644
--- a/doc/configuration.rst
+++ b/doc/configuration.rst
@@ -254,6 +254,25 @@ This parameter is optional but you must ensure it is set to ``False``
 The default configuration file provided by the ``modoboa-admin.py``
 command is properly configured.
 
+**********************
+Logging authentication
+**********************
+
+To trace login attempts to the web interface, Modoboa uses python
+`SysLogHandler <https://docs.python.org/3/library/logging.handlers.html#logging.handlers.SysLogHandler>`_
+so you can see them in your syslog authentication log file
+(`/var/log/auth.log` in most cases).
+
+Depending on your configuration, you may have to edit the :file:`settings.py` file
+and add `'address': '/dev/log'` to the logging section::
+
+    'syslog-auth': {
+        'class': 'logging.handlers.SysLogHandler',
+        'facility': SysLogHandler.LOG_AUTH,
+        'address': '/dev/log',
+        'formatter': 'syslog'
+    },
+
 ***********************
 External authentication
 ***********************
diff --git a/doc/manual_installation/modoboa.rst b/doc/manual_installation/modoboa.rst
index 5387a851b..9f37e8580 100644
--- a/doc/manual_installation/modoboa.rst
+++ b/doc/manual_installation/modoboa.rst
@@ -32,15 +32,25 @@ Modoboa depends on external tools and some of them require compilation
 so you need a compiler and a few C libraries. Make sure to install the
 following system packages according to your distribution:
 
-+------------------------------+------------------------------+
-|Debian/Ubuntu                 |CentOS                        |
-+==============================+==============================+
-|build-essential, python-dev,  |gcc, gcc-c++, python-devel,   |
-|libxml2-dev, libxslt-dev,     |libxml2-devel, libxslt-devel, |
-|libjpeg-dev, librrd-dev,      |libjpeg-turbo-devel,          |
-|rrdtool, libffi-dev           |rrdtool-devel, rrdtool,       |
-|                              |libffi-devel                  |
-+------------------------------+------------------------------+
++------------------------------+
+|Debian / Ubuntu               |
++==============================+
+|build-essential python-dev    |
+|libxml2-dev libxslt-dev       |
+|libjpeg-dev librrd-dev        |
+|rrdtool libffi-dev            |
+|                              |
++------------------------------+
+
++------------------------------+
+|CentOS                        |
++==============================+
+|gcc gcc-c++ python-devel      |
+|libxml2-devel libxslt-devel   |
+|libjpeg-turbo-devel           |
+|rrdtool-devel rrdtool         |
+|libffi-devel                  |
++------------------------------+
 
 Then, install Modoboa:
 
diff --git a/doc/manual_installation/webserver.rst b/doc/manual_installation/webserver.rst
index a95fef147..8f528fb88 100644
--- a/doc/manual_installation/webserver.rst
+++ b/doc/manual_installation/webserver.rst
@@ -168,15 +168,8 @@ uwsgi:
 
 .. warning:: 
 
-   Some distributions, including Debian and Ubuntu, ship an outdated
-   version of uWSGI that does not conform to the WSGI
-   specification. Versions prior to 1.2.6 do not call close on the
-   response object after handling a request. In those cases the
-   request_finished signal isn’t sent. This can result in idle
-   connections to database and memcache servers.
-
-Use uwsgi 1.2.6 or newer. If you do not, you *will* run into
-problems. Modoboa will fail in obscure ways.
+   Use uwsgi 1.2.6 or newer. If you do not, you *will* run into
+   problems. Modoboa will fail in obscure ways.
 
 To use this setup, first `download and install uwsgi
 <http://uwsgi-docs.readthedocs.org/en/latest/WSGIquickstart.html>`_.
diff --git a/doc/upgrade.rst b/doc/upgrade.rst
index 426b63be8..8c21065ae 100644
--- a/doc/upgrade.rst
+++ b/doc/upgrade.rst
@@ -185,6 +185,12 @@ Replace ``<driver>`` and ``<path>`` by your values.
 
 If ``transport_maps`` contains ``sql-relaydomains-transport.cf``, remove it.
 
+.. warning::
+
+   If you make use of postfix's `proxymap server
+   <http://www.postfix.org/proxymap.8.html>`_, you must also update
+   the ``proxy_read_maps`` setting.
+
 Reload postfix.
 
 Add the following cron job in order to generate DKIM keys::
diff --git a/modoboa/__init__.py b/modoboa/__init__.py
index 5d2abec9b..ad361c484 100644
--- a/modoboa/__init__.py
+++ b/modoboa/__init__.py
@@ -4,8 +4,7 @@
 
 from __future__ import unicode_literals
 
-from pkg_resources import get_distribution, DistributionNotFound
-
+from pkg_resources import DistributionNotFound, get_distribution
 
 try:
     __version__ = get_distribution(__name__).version
diff --git a/modoboa/admin/__init__.py b/modoboa/admin/__init__.py
index 5882e6d25..80f7ae2d3 100644
--- a/modoboa/admin/__init__.py
+++ b/modoboa/admin/__init__.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 default_app_config = "modoboa.admin.apps.AdminConfig"
diff --git a/modoboa/admin/api.py b/modoboa/admin/api.py
index a0e91e439..fed9bea69 100644
--- a/modoboa/admin/api.py
+++ b/modoboa/admin/api.py
@@ -1,21 +1,20 @@
+# -*- coding: utf-8 -*-
+
 """Admin API."""
 
 from __future__ import unicode_literals
 
 from django import http
-
 from django.contrib.contenttypes.models import ContentType
 
 from rest_framework import filters, status, viewsets
 from rest_framework.decorators import detail_route, list_route
 from rest_framework.exceptions import ParseError
-from rest_framework.permissions import IsAuthenticated, DjangoModelPermissions
+from rest_framework.permissions import DjangoModelPermissions, IsAuthenticated
 from rest_framework.response import Response
 
 from modoboa.core import models as core_models
-
-from . import models
-from . import serializers
+from . import models, serializers
 
 
 class DomainViewSet(viewsets.ModelViewSet):
@@ -81,7 +80,7 @@ class AccountViewSet(viewsets.ModelViewSet):
         user = self.request.user
         ids = user.objectaccess_set \
             .filter(content_type=ContentType.objects.get_for_model(user)) \
-            .values_list('object_id', flat=True)
+            .values_list("object_id", flat=True)
         queryset = core_models.User.objects.filter(pk__in=ids)
         domain = self.request.query_params.get("domain")
         if domain:
@@ -139,7 +138,7 @@ class AliasViewSet(viewsets.ModelViewSet):
         ids = (
             user.objectaccess_set.filter(
                 content_type=ContentType.objects.get_for_model(models.Alias))
-            .values_list('object_id', flat=True)
+            .values_list("object_id", flat=True)
         )
         queryset = models.Alias.objects.filter(pk__in=ids)
         domain = self.request.query_params.get("domain")
diff --git a/modoboa/admin/app_settings.py b/modoboa/admin/app_settings.py
index a72dd7fff..cd1afa3e7 100644
--- a/modoboa/admin/app_settings.py
+++ b/modoboa/admin/app_settings.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa admin settings."""
 
 from __future__ import unicode_literals
@@ -6,13 +8,12 @@ import os
 
 from django import forms
 from django.conf import settings
-from django.utils.translation import ugettext as _, ugettext_lazy
 from django.utils.encoding import force_text
+from django.utils.translation import ugettext as _, ugettext_lazy
 
-from modoboa.lib.form_utils import YesNoField, SeparatorField
+from modoboa.lib.form_utils import SeparatorField, YesNoField
 from modoboa.lib.sysutils import exec_cmd
 from modoboa.parameters import forms as param_forms
-
 from . import constants
 
 
diff --git a/modoboa/admin/apps.py b/modoboa/admin/apps.py
index f799fa177..77ba62271 100644
--- a/modoboa/admin/apps.py
+++ b/modoboa/admin/apps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """AppConfig for admin."""
 
 from __future__ import unicode_literals
@@ -17,4 +19,4 @@ class AdminConfig(AppConfig):
     def ready(self):
         load_admin_settings()
 
-        from . import handlers
+        from . import handlers  # NOQA:F401
diff --git a/modoboa/admin/constants.py b/modoboa/admin/constants.py
index 372f1ef20..e6f1c4e40 100644
--- a/modoboa/admin/constants.py
+++ b/modoboa/admin/constants.py
@@ -1,10 +1,11 @@
+# -*- coding: utf-8 -*-
+
 """Admin constants."""
 
 from __future__ import unicode_literals
 
 from django.utils.translation import ugettext_lazy as _
 
-
 DNSBL_PROVIDERS = [
     "aspews.ext.sorbs.net",
     "b.barracudacentral.org",
diff --git a/modoboa/admin/factories.py b/modoboa/admin/factories.py
index b62ba877a..e0d5780c8 100644
--- a/modoboa/admin/factories.py
+++ b/modoboa/admin/factories.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """
 Fixtures factories.
 """
@@ -18,7 +20,7 @@ class DomainFactory(PermissionFactory):
         model = models.Domain
         django_get_or_create = ("name", )
 
-    type = "domain"
+    type = "domain"  # NOQA:A003
     quota = 0
     default_mailbox_quota = 10
     enabled = True
@@ -79,44 +81,44 @@ def populate_database():
     """
     dom = DomainFactory(name="test.com", quota=50)
     admin = UserFactory(
-        username="admin@test.com", groups=('DomainAdmins', ),
-        password='{PLAIN}toto'
+        username="admin@test.com", groups=("DomainAdmins", ),
+        password="{PLAIN}toto"
     )
-    MailboxFactory(address='admin', domain=dom, user=admin)
+    MailboxFactory(address="admin", domain=dom, user=admin)
     account = UserFactory.create(
-        username="user@test.com", groups=('SimpleUsers',),
+        username="user@test.com", groups=("SimpleUsers",),
     )
-    MailboxFactory.create(address='user', domain=dom, user=account)
+    MailboxFactory.create(address="user", domain=dom, user=account)
 
     al = AliasFactory.create(
-        address='forward@test.com', domain=dom
+        address="forward@test.com", domain=dom
     )
     AliasRecipientFactory.create(
-        address='user@external.com', alias=al)
+        address="user@external.com", alias=al)
 
     al = AliasFactory.create(
-        address='alias@test.com', domain=dom
+        address="alias@test.com", domain=dom
     )
     mb = account.mailbox
     AliasRecipientFactory.create(
         address=mb.full_address, alias=al, r_mailbox=mb)
 
     al = AliasFactory.create(
-        address='postmaster@test.com', domain=dom
+        address="postmaster@test.com", domain=dom
     )
-    for address in ['toto@titi.com', 'test@truc.fr']:
+    for address in ["toto@titi.com", "test@truc.fr"]:
         AliasRecipientFactory.create(address=address, alias=al)
 
     dom.add_admin(admin)
 
-    dom2 = DomainFactory.create(name='test2.com', default_mailbox_quota=0)
+    dom2 = DomainFactory.create(name="test2.com", default_mailbox_quota=0)
     admin = UserFactory.create(
-        username='admin@test2.com', groups=('DomainAdmins',),
-        password='{PLAIN}toto'
+        username="admin@test2.com", groups=("DomainAdmins",),
+        password="{PLAIN}toto"
     )
-    MailboxFactory.create(address='admin', domain=dom2, user=admin)
+    MailboxFactory.create(address="admin", domain=dom2, user=admin)
     u = UserFactory.create(
-        username='user@test2.com', groups=('SimpleUsers',)
+        username="user@test2.com", groups=("SimpleUsers",)
     )
-    MailboxFactory.create(address='user', domain=dom2, user=u)
+    MailboxFactory.create(address="user", domain=dom2, user=u)
     dom2.add_admin(admin)
diff --git a/modoboa/admin/forms/__init__.py b/modoboa/admin/forms/__init__.py
index b7811a0d9..bb1ded79a 100644
--- a/modoboa/admin/forms/__init__.py
+++ b/modoboa/admin/forms/__init__.py
@@ -1,21 +1,23 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
-from .domain import (
-    DomainFormGeneral, DomainFormOptions, DomainForm, DomainWizard
-)
 from .account import (
-    AccountFormGeneral, AccountFormMail, AccountPermissionsForm,
-    AccountForm, AccountWizard
+    AccountForm, AccountFormGeneral, AccountFormMail, AccountPermissionsForm,
+    AccountWizard
 )
 from .alias import AliasForm
+from .domain import (
+    DomainForm, DomainFormGeneral, DomainFormOptions, DomainWizard
+)
+from .export import ExportDataForm, ExportDomainsForm, ExportIdentitiesForm
 from .forward import ForwardForm
 from .import_ import ImportDataForm, ImportIdentitiesForm
-from .export import ExportDataForm, ExportDomainsForm, ExportIdentitiesForm
 
 __all__ = [
-    'DomainFormGeneral', 'DomainFormOptions', 'DomainForm',
-    'AccountFormGeneral', 'AccountFormMail', 'AccountPermissionsForm',
-    'AccountForm', 'AliasForm', 'ImportDataForm', 'ImportIdentitiesForm',
-    'ExportDataForm', 'ExportDomainsForm', 'ExportIdentitiesForm',
-    'ForwardForm', 'DomainWizard', 'AccountWizard'
+    "DomainFormGeneral", "DomainFormOptions", "DomainForm",
+    "AccountFormGeneral", "AccountFormMail", "AccountPermissionsForm",
+    "AccountForm", "AliasForm", "ImportDataForm", "ImportIdentitiesForm",
+    "ExportDataForm", "ExportDomainsForm", "ExportIdentitiesForm",
+    "ForwardForm", "DomainWizard", "AccountWizard"
 ]
diff --git a/modoboa/admin/forms/account.py b/modoboa/admin/forms/account.py
index 1622a8f62..0fa0ab3c7 100644
--- a/modoboa/admin/forms/account.py
+++ b/modoboa/admin/forms/account.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Forms related to accounts management."""
 
 from __future__ import unicode_literals
@@ -7,17 +9,15 @@ from functools import reduce
 
 from django import forms
 from django.conf import settings
+from django.contrib.auth import password_validation
 from django.http import QueryDict
 from django.urls import reverse
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from django.contrib.auth import password_validation
-
 from modoboa.core import signals as core_signals
 from modoboa.core.models import User
+from modoboa.lib import exceptions as lib_exceptions, fields as lib_fields
 from modoboa.lib.email_utils import split_mailbox
-from modoboa.lib import exceptions as lib_exceptions
-from modoboa.lib import fields as lib_fields
 from modoboa.lib.form_utils import (
     DynamicForm, TabForms, WizardForm, WizardStep
 )
@@ -25,10 +25,7 @@ from modoboa.lib.permissions import get_account_roles
 from modoboa.lib.validators import validate_utf8_email
 from modoboa.lib.web_utils import render_to_json_response
 from modoboa.parameters import tools as param_tools
-
-from .. import lib
-from .. import models
-from .. import signals
+from .. import lib, models, signals
 
 
 class AccountFormGeneral(forms.ModelForm):
@@ -527,9 +524,9 @@ class AccountForm(TabForms):
     def extra_context(self, context):
         account = self.instances["general"]
         context.update({
-            'title': account.username,
-            'formid': 'accountform',
-            'action': reverse("admin:account_change",
+            "title": account.username,
+            "formid": "accountform",
+            "action": reverse("admin:account_change",
                               args=[account.id]),
         })
 
@@ -604,9 +601,9 @@ class AccountWizard(WizardForm):
 
     def extra_context(self, context):
         context.update({
-            'title': _("New account"),
-            'action': reverse("admin:account_add"),
-            'formid': 'newaccount_form'
+            "title": _("New account"),
+            "action": reverse("admin:account_add"),
+            "formid": "newaccount_form"
         })
 
     def done(self):
diff --git a/modoboa/admin/forms/alias.py b/modoboa/admin/forms/alias.py
index 12b306442..09ee606e4 100644
--- a/modoboa/admin/forms/alias.py
+++ b/modoboa/admin/forms/alias.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Forms related to aliases management."""
 
 from __future__ import unicode_literals
@@ -9,14 +11,10 @@ from django.http import QueryDict
 from django.utils.translation import ugettext as _, ugettext_lazy
 
 from modoboa.core import signals as core_signals
-from modoboa.lib import exceptions as lib_exceptions
+from modoboa.lib import exceptions as lib_exceptions, fields as lib_fields
 from modoboa.lib.email_utils import split_mailbox
-from modoboa.lib import fields as lib_fields
-from modoboa.lib.form_utils import (
-    DynamicForm
-)
-
-from ..models import Domain, Alias
+from modoboa.lib.form_utils import DynamicForm
+from ..models import Alias, Domain
 
 
 class AliasForm(forms.ModelForm, DynamicForm):
diff --git a/modoboa/admin/forms/domain.py b/modoboa/admin/forms/domain.py
index ddd4bf070..5cc3f4a9d 100644
--- a/modoboa/admin/forms/domain.py
+++ b/modoboa/admin/forms/domain.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Forms related to domains management."""
 
 from __future__ import unicode_literals
@@ -5,34 +7,28 @@ from __future__ import unicode_literals
 from functools import reduce
 
 from django import forms
-from django.urls import reverse
 from django.http import QueryDict
-from django.utils.translation import ugettext as _, ugettext_lazy
+from django.urls import reverse
 from django.utils.encoding import force_text
+from django.utils.translation import ugettext as _, ugettext_lazy
 
 from modoboa.core import signals as core_signals
 from modoboa.core.models import User
 from modoboa.lib.exceptions import Conflict
 from modoboa.lib.fields import DomainNameField
 from modoboa.lib.form_utils import (
-    YesNoField, WizardForm, WizardStep, DynamicForm, TabForms
+    DynamicForm, TabForms, WizardForm, WizardStep, YesNoField
 )
 from modoboa.lib.web_utils import render_to_json_response
 from modoboa.parameters import tools as param_tools
-
-from .. import constants
-from .. import lib
-from .. import signals
-
-from ..models import (
-    Domain, DomainAlias, Mailbox, Alias
-)
+from .. import constants, lib, signals
+from ..models import Alias, Domain, DomainAlias, Mailbox
 
 
 class DomainFormGeneral(forms.ModelForm, DynamicForm):
     """A form to create/edit a domain."""
 
-    type = forms.ChoiceField(
+    type = forms.ChoiceField(  # NOQA:A003
         label=ugettext_lazy("Type"),
     )
     aliases = DomainNameField(
@@ -82,7 +78,7 @@ class DomainFormGeneral(forms.ModelForm, DynamicForm):
         """Check unicity and more."""
         name = self.cleaned_data["name"]
         label = lib.check_if_domain_exists(
-            name, [(DomainAlias, _('domain alias'))])
+            name, [(DomainAlias, _("domain alias"))])
         if label is not None:
             raise forms.ValidationError(
                 _("A %s with this name already exists") % force_text(label))
diff --git a/modoboa/admin/forms/export.py b/modoboa/admin/forms/export.py
index 25e9402a3..1a295c599 100644
--- a/modoboa/admin/forms/export.py
+++ b/modoboa/admin/forms/export.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from django import forms
diff --git a/modoboa/admin/forms/forward.py b/modoboa/admin/forms/forward.py
index ddccba0f4..b270fb32d 100644
--- a/modoboa/admin/forms/forward.py
+++ b/modoboa/admin/forms/forward.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Forms related to forwards management."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/admin/forms/import_.py b/modoboa/admin/forms/import_.py
index 790260919..db50913ff 100644
--- a/modoboa/admin/forms/import_.py
+++ b/modoboa/admin/forms/import_.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Forms related to import operations."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/admin/handlers.py b/modoboa/admin/handlers.py
index a91a12667..14b499eb8 100644
--- a/modoboa/admin/handlers.py
+++ b/modoboa/admin/handlers.py
@@ -1,27 +1,21 @@
+# -*- coding: utf-8 -*-
+
 """Django signal handlers for admin."""
 
 from __future__ import unicode_literals
 
-from django.urls import reverse
+from django.contrib.contenttypes.models import ContentType
 from django.db.models import signals
 from django.dispatch import receiver
+from django.urls import reverse
 from django.utils.translation import ugettext as _
 
-from django.contrib.contenttypes.models import ContentType
-
-from modoboa.core import models as core_models
-from modoboa.core import signals as core_signals
+from modoboa.core import models as core_models, signals as core_signals
+from modoboa.lib import exceptions, permissions, signals as lib_signals
 from modoboa.lib.cryptutils import encrypt
 from modoboa.lib.email_utils import split_mailbox
-from modoboa.lib import exceptions
-from modoboa.lib import permissions
-from modoboa.lib import signals as lib_signals
 from modoboa.parameters import tools as param_tools
-
-from . import signals as admin_signals
-from . import lib
-from . import models
-from . import postfix_maps
+from . import lib, models, postfix_maps, signals as admin_signals
 
 
 @receiver(signals.post_save, sender=models.Domain)
@@ -161,7 +155,7 @@ def account_auto_created(sender, user, **kwargs):
     if not param_tools.get_global_parameter("auto_create_domain_and_mailbox"):
         return
     localpart, domname = split_mailbox(user.username)
-    if user.role != 'SimpleUsers' and domname is None:
+    if user.role != "SimpleUsers" and domname is None:
         return
     sadmins = core_models.User.objects.filter(is_superuser=True)
     try:
diff --git a/modoboa/admin/lib.py b/modoboa/admin/lib.py
index e85ca33cc..2b1819bed 100644
--- a/modoboa/admin/lib.py
+++ b/modoboa/admin/lib.py
@@ -4,30 +4,28 @@
 
 from __future__ import unicode_literals
 
-from functools import wraps
 import ipaddress
-from itertools import chain
 import logging
 import random
 import socket
 import string
+from functools import wraps
+from itertools import chain
 
-from dns.name import IDNA_2008_UTS_46
 import dns.resolver
+from dns.name import IDNA_2008_UTS_46
 
 from django.contrib.contenttypes.models import ContentType
 from django.db.models import Q
 from django.utils.encoding import smart_text
 from django.utils.translation import ugettext as _
 
-from modoboa.core.models import User
 from modoboa.core import signals as core_signals
+from modoboa.core.models import User
 from modoboa.lib.exceptions import PermDeniedException
 from modoboa.parameters import tools as param_tools
-
-from .models import Domain, DomainAlias, Alias
-
 from . import signals
+from .models import Alias, Domain, DomainAlias
 
 
 def needs_mailbox():
@@ -59,7 +57,7 @@ def get_identities(user, searchquery=None, idtfilter=None, grpfilter=None):
     if idtfilter is None or not idtfilter or idtfilter == "account":
         ids = user.objectaccess_set \
             .filter(content_type=ContentType.objects.get_for_model(user)) \
-            .values_list('object_id', flat=True)
+            .values_list("object_id", flat=True)
         q = Q(pk__in=ids)
         if searchquery is not None:
             q &= Q(username__icontains=searchquery) \
@@ -76,7 +74,7 @@ def get_identities(user, searchquery=None, idtfilter=None, grpfilter=None):
             or (idtfilter in ["alias", "forward", "dlist"]):
         alct = ContentType.objects.get_for_model(Alias)
         ids = user.objectaccess_set.filter(content_type=alct) \
-            .values_list('object_id', flat=True)
+            .values_list("object_id", flat=True)
         q = Q(pk__in=ids, internal=False)
         if searchquery is not None:
             q &= (
@@ -187,8 +185,8 @@ def get_domain_mx_list(domain):
         logger.error(_("No working name servers found"), exc_info=e)
     except dns.resolver.Timeout as e:
         logger.warning(
-            _("DNS resolution timeout, unable to query %s at the moment") % domain,
-            exc_info=e)
+            _("DNS resolution timeout, unable to query %s at the moment") %
+            domain, exc_info=e)
     else:
         for dns_answer in dns_answers:
             try:
@@ -225,7 +223,7 @@ def domain_has_authorized_mx(name):
     valid_mxs = [ipaddress.ip_network(smart_text(v.strip()))
                  for v in valid_mxs.split() if v.strip()]
     domain_mxs = get_domain_mx_list(name)
-    for mx_addr, mx_ip_addr in domain_mxs:  # noqa:B007
+    for _mx_addr, mx_ip_addr in domain_mxs:
         for subnet in valid_mxs:
             if mx_ip_addr in subnet:
                 return True
diff --git a/modoboa/admin/management/__init__.py b/modoboa/admin/management/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/admin/management/__init__.py
+++ b/modoboa/admin/management/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/admin/management/commands/__init__.py b/modoboa/admin/management/commands/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/admin/management/commands/__init__.py
+++ b/modoboa/admin/management/commands/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/admin/management/commands/handle_mailbox_operations.py b/modoboa/admin/management/commands/handle_mailbox_operations.py
index 8888cb9eb..15d8f6e11 100644
--- a/modoboa/admin/management/commands/handle_mailbox_operations.py
+++ b/modoboa/admin/management/commands/handle_mailbox_operations.py
@@ -1,6 +1,8 @@
+# -*- coding: utf-8 -*-
+
 """A management command to apply mailbox operations."""
 
-from __future__ import unicode_literals, print_function
+from __future__ import print_function, unicode_literals
 
 import logging
 import os
@@ -8,10 +10,9 @@ import shutil
 
 from django.core.management.base import BaseCommand
 
-from modoboa.parameters import tools as param_tools
-from modoboa.lib.sysutils import exec_cmd
 from modoboa.lib.exceptions import InternalError
-
+from modoboa.lib.sysutils import exec_cmd
+from modoboa.parameters import tools as param_tools
 from ...app_settings import load_admin_settings
 from ...models import MailboxOperation
 
@@ -25,7 +26,7 @@ class OperationError(Exception):
 class Command(BaseCommand):
     """Command definition"""
 
-    help = "Handles rename and delete operations on mailboxes"
+    help = "Handles rename and delete operations on mailboxes"  # NOQA:A003
 
     def __init__(self, *args, **kwargs):
         super(Command, self).__init__(*args, **kwargs)
@@ -80,7 +81,7 @@ class Command(BaseCommand):
             )
             if not code:
                 return False
-        with open(path, 'w') as fp:
+        with open(path, "w") as fp:
             print(os.getpid(), file=fp)
         return True
 
diff --git a/modoboa/admin/management/commands/modo.py b/modoboa/admin/management/commands/modo.py
index d395c4c19..b4f3495f5 100644
--- a/modoboa/admin/management/commands/modo.py
+++ b/modoboa/admin/management/commands/modo.py
@@ -1,13 +1,15 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa main management command."""
 
 from __future__ import unicode_literals
 
 from subcommand.base import SubcommandCommand
 
-from .subcommands._mx import CheckMXRecords
 from .subcommands._export import ExportCommand
 from .subcommands._import import ImportCommand
 from .subcommands._manage_dkim_keys import ManageDKIMKeys
+from .subcommands._mx import CheckMXRecords
 from .subcommands._repair import Repair
 
 
@@ -17,7 +19,7 @@ class Command(SubcommandCommand):
     $ python manage.py modo
     """
 
-    help = "Modoboa top management command."
+    help = "Modoboa top management command."  # NOQA:A003
 
     subcommands = {
         "export": ExportCommand,
diff --git a/modoboa/admin/management/commands/subcommands/__init__.py b/modoboa/admin/management/commands/subcommands/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/admin/management/commands/subcommands/__init__.py
+++ b/modoboa/admin/management/commands/subcommands/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/admin/management/commands/subcommands/_export.py b/modoboa/admin/management/commands/subcommands/_export.py
index bad0e0afd..15ff8cf2a 100644
--- a/modoboa/admin/management/commands/subcommands/_export.py
+++ b/modoboa/admin/management/commands/subcommands/_export.py
@@ -1,21 +1,28 @@
+# -*- coding: utf-8 -*-
+
 """Django management command to export admin objects."""
 
 from __future__ import unicode_literals
 
-from backports import csv
 import sys
 
 from django.core.management.base import BaseCommand
+from django.utils import six
 
-from modoboa.core.models import User
 from modoboa.core.extensions import exts_pool
+from modoboa.core.models import User
 from .... import models
 
+if six.PY2:
+    from backports import csv
+else:
+    import csv
+
 
 class ExportCommand(BaseCommand):
     """Command class."""
 
-    help = "Export domains or identities using CSV format"  # noqa:A003
+    help = "Export domains or identities using CSV format"  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add arguments to command."""
@@ -46,12 +53,12 @@ class ExportCommand(BaseCommand):
             dumped_aliases += [alias.pk]
         qset = (
             models.Alias.objects.exclude(pk__in=dumped_aliases)
-            .prefetch_related('aliasrecipient_set')
+            .prefetch_related("aliasrecipient_set")
         )
         for alias in qset:
             alias.to_csv(self.csvwriter)
 
     def handle(self, *args, **options):
         exts_pool.load_all()
-        self.csvwriter = csv.writer(sys.stdout, delimiter=options['sepchar'])
+        self.csvwriter = csv.writer(sys.stdout, delimiter=options["sepchar"])
         getattr(self, "export_{}".format(options["objtype"]))()
diff --git a/modoboa/admin/management/commands/subcommands/_import.py b/modoboa/admin/management/commands/subcommands/_import.py
index 1c9c16d89..a202fe22b 100644
--- a/modoboa/admin/management/commands/subcommands/_import.py
+++ b/modoboa/admin/management/commands/subcommands/_import.py
@@ -1,58 +1,69 @@
+# -*- coding: utf-8 -*-
+
 """Django management command to import admin objects."""
 
 from __future__ import unicode_literals
 
-from backports import csv
 import io
 import os
 
 import progressbar
+from chardet.universaldetector import UniversalDetector
 
 from django.core.management.base import BaseCommand, CommandError
+from django.db import transaction
+from django.utils import six
+from django.utils.translation import ugettext as _
 
 from modoboa.core import models as core_models
 from modoboa.core.extensions import exts_pool
 from modoboa.lib.exceptions import Conflict
-
 from .... import signals
 
+if six.PY2:
+    from backports import csv
+else:
+    import csv
+
 
 class ImportCommand(BaseCommand):
     """Command class."""
 
     args = "csvfile"
-    help = "Import identities from a csv file"  # noqa:A003
+    help = "Import identities from a csv file"  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add extra arguments to command."""
         parser.add_argument(
-            "--sepchar", type=str, default=";",
+            "--sepchar", type=six.text_type, default=";",
             help="Separator used in file.")
         parser.add_argument(
             "--continue-if-exists", action="store_true",
-            dest='continue_if_exists', default=False,
+            dest="continue_if_exists", default=False,
             help="Continue even if an entry already exists.")
         parser.add_argument(
             "--crypt-password", action="store_true",
             default=False, help="Encrypt provided passwords.")
         parser.add_argument(
-            "files", type=str, nargs="+", help="CSV files to import.")
+            "files", type=six.text_type, nargs="+", help="CSV files to import.")
 
-    def _import(self, filename, options):
+    def _import(self, filename, options, encoding="utf-8"):
         """Import domains or identities."""
         superadmin = (
             core_models.User.objects.filter(is_superuser=True).first()
         )
-        if not os.path.exists(filename):
+        if not os.path.isfile(filename):
             raise CommandError("File not found")
 
-        num_lines = sum(1 for line in open(filename) if line)
+        num_lines = sum(
+            1 for line in io.open(filename, encoding=encoding) if line
+        )
         pbar = progressbar.ProgressBar(
             widgets=[
                 progressbar.Percentage(), progressbar.Bar(), progressbar.ETA()
             ], maxval=num_lines
         ).start()
-        with io.open(filename, encoding="utf8") as f:
+        with io.open(filename, encoding=encoding, newline="") as f:
             reader = csv.reader(f, delimiter=options["sepchar"])
             i = 0
             for row in reader:
@@ -81,4 +92,39 @@ class ImportCommand(BaseCommand):
         """Command entry point."""
         exts_pool.load_all()
         for filename in options["files"]:
-            self._import(filename, options)
+            try:
+                with transaction.atomic():
+                    self._import(filename, options)
+            except CommandError as exc:
+                raise exc
+            except UnicodeDecodeError:
+                self.stdout.write(self.style.NOTICE(
+                    _("CSV file is not encoded in UTF-8, attempting to guess "
+                      "encoding")
+                ))
+                detector = UniversalDetector()
+                with io.open(filename, "rb") as fp:
+                    for line in fp:
+                        detector.feed(line)
+                        if detector.done:
+                            break
+                    detector.close()
+
+                self.stdout.write(self.style.NOTICE(
+                    _("Reading CSV file using %(encoding)s encoding") %
+                    detector.result
+                ))
+                try:
+                    with transaction.atomic():
+                        self._import(
+                            filename, options,
+                            encoding=detector.result["encoding"]
+                        )
+                except UnicodeDecodeError as exc:
+                    six.raise_from(
+                        CommandError(
+                            _("Unable to decode CSV file using %(encoding)s "
+                              "encoding") % detector.result
+                        ),
+                        exc
+                    )
diff --git a/modoboa/admin/management/commands/subcommands/_manage_dkim_keys.py b/modoboa/admin/management/commands/subcommands/_manage_dkim_keys.py
index bae55519c..c7002c2c0 100644
--- a/modoboa/admin/management/commands/subcommands/_manage_dkim_keys.py
+++ b/modoboa/admin/management/commands/subcommands/_manage_dkim_keys.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Management command to create DKIM keys."""
 
 from __future__ import print_function, unicode_literals
@@ -11,6 +13,7 @@ from modoboa.lib import sysutils
 from modoboa.parameters import tools as param_tools
 
 from .... import models
+from .... import signals
 
 
 class ManageDKIMKeys(BaseCommand):
@@ -50,3 +53,5 @@ class ManageDKIMKeys(BaseCommand):
             enable_dkim=True, dkim_private_key_path="")
         for domain in qset:
             self.create_new_dkim_key(domain)
+        if qset.exists():
+            signals.new_dkim_keys.send(sender=self.__class__, domains=qset)
diff --git a/modoboa/admin/management/commands/subcommands/_mx.py b/modoboa/admin/management/commands/subcommands/_mx.py
index b7ce24fd1..8f0db645e 100644
--- a/modoboa/admin/management/commands/subcommands/_mx.py
+++ b/modoboa/admin/management/commands/subcommands/_mx.py
@@ -18,15 +18,14 @@ from django.utils.encoding import smart_text
 from django.utils.functional import cached_property
 from django.utils.translation import ugettext as _
 
-from modoboa.admin import constants
-from modoboa.admin import models
+from modoboa.admin import constants, models
 from modoboa.parameters import tools as param_tools
 
 
 class CheckMXRecords(BaseCommand):
     """Command class."""
 
-    help = "Check defined domains."  # noqa:A003
+    help = "Check defined domains."  # NOQA:A003
 
     @cached_property
     def providers(self):
diff --git a/modoboa/admin/management/commands/subcommands/_repair.py b/modoboa/admin/management/commands/subcommands/_repair.py
index 1406b683d..26bfb42f4 100644
--- a/modoboa/admin/management/commands/subcommands/_repair.py
+++ b/modoboa/admin/management/commands/subcommands/_repair.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Management command to check and fix known problems."""
 
 from __future__ import print_function, unicode_literals
@@ -6,11 +8,9 @@ from django.conf import settings
 from django.core.management.base import BaseCommand
 from django.utils.encoding import smart_str
 
-from modoboa.lib.permissions import grant_access_to_object
-from modoboa.lib.permissions import get_object_owner
-
-from modoboa.core.models import User
 from modoboa.admin import models
+from modoboa.core.models import User
+from modoboa.lib.permissions import get_object_owner, grant_access_to_object
 
 known_problems = []
 
@@ -97,7 +97,7 @@ def sometimes_mailbox_have_no_alias(**options):
 class Repair(BaseCommand):
     """Command class."""
 
-    help = "Check and fix known problems."
+    help = "Check and fix known problems."  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add extra arguments to command."""
@@ -113,7 +113,10 @@ class Repair(BaseCommand):
         # Load known problems from extensions.
         for ext in settings.MODOBOA_APPS:
             try:
-                __import__(ext, locals(), globals(), [smart_str("known_problems")])
+                __import__(
+                    ext, locals(), globals(),
+                    [smart_str("known_problems")]
+                )
             except ImportError:
                 pass
         for func in known_problems:
diff --git a/modoboa/admin/models/__init__.py b/modoboa/admin/models/__init__.py
index ead319150..068fc45e9 100644
--- a/modoboa/admin/models/__init__.py
+++ b/modoboa/admin/models/__init__.py
@@ -1,13 +1,15 @@
+# -*- coding: utf-8 -*-
+
 """Admin models."""
 
 from __future__ import unicode_literals
 
+from .alias import Alias, AliasRecipient
 from .base import AdminObject
 from .domain import Domain
 from .domain_alias import DomainAlias
-from .mailbox import Mailbox, Quota, MailboxOperation, SenderAddress
+from .mailbox import Mailbox, MailboxOperation, Quota, SenderAddress
 from .mxrecord import DNSBLResult, MXRecord
-from .alias import Alias, AliasRecipient
 
 __all__ = [
     "AdminObject",
diff --git a/modoboa/admin/models/alias.py b/modoboa/admin/models/alias.py
index 225ed9e78..3056d6155 100644
--- a/modoboa/admin/models/alias.py
+++ b/modoboa/admin/models/alias.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Models related to aliases management."""
 
 from __future__ import unicode_literals
@@ -5,25 +7,24 @@ from __future__ import unicode_literals
 import hashlib
 import random
 
-from django.urls import reverse
+from reversion import revisions as reversion
+
 from django.db import models
+from django.urls import reverse
 from django.utils.encoding import (
-    python_2_unicode_compatible, smart_text, force_str, force_bytes
+    force_bytes, force_str, python_2_unicode_compatible, smart_text
 )
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from reversion import revisions as reversion
-
 from modoboa.core import signals as core_signals
 from modoboa.lib.email_utils import split_mailbox
 from modoboa.lib.exceptions import (
-    PermDeniedException, BadRequest, Conflict, NotFound
+    BadRequest, Conflict, NotFound, PermDeniedException
 )
-
+from .. import signals
 from .base import AdminObject
 from .domain import Domain
 from .mailbox import Mailbox
-from .. import signals
 
 
 @python_2_unicode_compatible
@@ -48,7 +49,7 @@ class Alias(AdminObject):
         ugettext_lazy("Description"), blank=True)
     expire_at = models.DateTimeField(
         ugettext_lazy("Expire at"), blank=True, null=True)
-    _objectname = 'MailboxAlias'
+    _objectname = "MailboxAlias"
 
     class Meta:
         permissions = (
@@ -139,7 +140,7 @@ class Alias(AdminObject):
                     domain=domain, address=local_part).first()
                 if rcpt is None:
                     rcpt = Alias.objects.filter(
-                        address='%s@%s' % (local_part, domname)
+                        address="%s@%s" % (local_part, domname)
                     ).first()
                     if rcpt is None:
                         raise NotFound(
diff --git a/modoboa/admin/models/base.py b/modoboa/admin/models/base.py
index 9ab6fc6c8..abe182180 100644
--- a/modoboa/admin/models/base.py
+++ b/modoboa/admin/models/base.py
@@ -1,12 +1,13 @@
+# -*- coding: utf-8 -*-
+
 """Base admin models."""
 
 from __future__ import unicode_literals
 
+from django.contrib.contenttypes.fields import GenericRelation
 from django.db import models
 from django.utils import timezone
 
-from django.contrib.contenttypes.fields import GenericRelation
-
 from modoboa.core import models as core_models
 from modoboa.lib.permissions import (
     grant_access_to_object, ungrant_access_to_object
diff --git a/modoboa/admin/models/domain.py b/modoboa/admin/models/domain.py
index fa0337a3a..60ee94427 100644
--- a/modoboa/admin/models/domain.py
+++ b/modoboa/admin/models/domain.py
@@ -1,33 +1,34 @@
+# -*- coding: utf-8 -*-
+
 """Models related to domains management."""
 
 from __future__ import unicode_literals
 
 import datetime
 
+from reversion import revisions as reversion
+
 from django.db import models
 from django.utils import timezone
 from django.utils.encoding import (
-    python_2_unicode_compatible, smart_text, force_text
+    force_text, python_2_unicode_compatible, smart_text
 )
 from django.utils.functional import cached_property
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from reversion import revisions as reversion
-
 from modoboa.core import signals as core_signals
 from modoboa.core.models import User
 from modoboa.lib.exceptions import BadRequest, Conflict
 from modoboa.parameters import tools as param_tools
-
-from .base import AdminObject
 from .. import constants
+from .base import AdminObject
 
 
 @python_2_unicode_compatible
 class Domain(AdminObject):
     """Mail domain."""
 
-    name = models.CharField(ugettext_lazy('name'), max_length=100, unique=True,
+    name = models.CharField(ugettext_lazy("name"), max_length=100, unique=True,
                             help_text=ugettext_lazy("The domain name"))
     quota = models.PositiveIntegerField(
         default=0,
@@ -45,11 +46,11 @@ class Domain(AdminObject):
         )
     )
     enabled = models.BooleanField(
-        ugettext_lazy('enabled'),
+        ugettext_lazy("enabled"),
         help_text=ugettext_lazy("Check to activate this domain"),
         default=True
     )
-    type = models.CharField(default="domain", max_length=20)
+    type = models.CharField(default="domain", max_length=20)  # NOQA:A003
     enable_dns_checks = models.BooleanField(
         ugettext_lazy("Enable DNS checks"), default=True,
         help_text=ugettext_lazy("Check to enable DNS checks for this domain")
@@ -205,8 +206,21 @@ class Domain(AdminObject):
     @property
     def bind_format_dkim_public_key(self):
         """Return DKIM public key using Bind format."""
-        return "{}._domainkey 10800 IN TXT \"v=DKIM1; k=rsa; p={}\"".format(
-            self.dkim_key_selector, self.dkim_public_key)
+        record = "v=DKIM1;k=rsa;p=%s" % self.dkim_public_key
+        # TXT records longer than 255 characters need split into chunks
+        # split record into 74 character chunks (+2 for indent, +2 for quotes(")
+        # == 78 characters) to make more readable in text editors.
+        split_record = []
+        while record:
+            if len(record) > 74:
+                split_record.append("  \"%s\"" % record[:74])
+                record = record[74:]
+            else:
+                split_record.append("  \"%s\"" % record)
+                break
+        record = "\n".join(split_record)
+        return "{}._domainkey.{}. 10800 IN TXT (\n{})".format(
+            self.dkim_key_selector, self.name, record)
 
     def add_admin(self, account):
         """Add a new administrator to this domain.
@@ -245,9 +259,9 @@ class Domain(AdminObject):
     def save(self, *args, **kwargs):
         """Store current data if domain is renamed."""
         if self.oldname != self.name:
-            self.old_mail_homes = (
-                dict((mb.id, mb.mail_home) for mb in self.mailbox_set.all())
-            )
+            self.old_mail_homes = {
+                mb.id: mb.mail_home for mb in self.mailbox_set.all()
+            }
         super(Domain, self).save(*args, **kwargs)
 
     def delete(self, fromuser, keepdir=False):
diff --git a/modoboa/admin/models/domain_alias.py b/modoboa/admin/models/domain_alias.py
index 51ccfba69..3fec21047 100644
--- a/modoboa/admin/models/domain_alias.py
+++ b/modoboa/admin/models/domain_alias.py
@@ -1,19 +1,18 @@
+# -*- coding: utf-8 -*-
+
 """Models related to domain aliases management."""
 
 from __future__ import unicode_literals
 
+from reversion import revisions as reversion
+
+from django.contrib.contenttypes.fields import GenericRelation
 from django.db import models
 from django.utils.encoding import python_2_unicode_compatible, smart_text
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from django.contrib.contenttypes.fields import GenericRelation
-
-from reversion import revisions as reversion
-
-from modoboa.core import models as core_models
-from modoboa.core import signals as core_signals
+from modoboa.core import models as core_models, signals as core_signals
 from modoboa.lib.exceptions import BadRequest, Conflict
-
 from .base import AdminObject
 from .domain import Domain
 
@@ -39,12 +38,12 @@ class DomainAlias(AdminObject):
     name = models.CharField(ugettext_lazy("name"), max_length=100, unique=True,
                             help_text=ugettext_lazy("The alias name"))
     target = models.ForeignKey(
-        Domain, verbose_name=ugettext_lazy('target'),
+        Domain, verbose_name=ugettext_lazy("target"),
         help_text=ugettext_lazy("The domain this alias points to"),
         on_delete=models.CASCADE
     )
     enabled = models.BooleanField(
-        ugettext_lazy('enabled'),
+        ugettext_lazy("enabled"),
         help_text=ugettext_lazy("Check to activate this alias"),
         default=True
     )
@@ -65,7 +64,8 @@ class DomainAlias(AdminObject):
     def from_csv(self, user, row):
         """Create a domain alias from a CSV row
 
-        Expected format: ["domainalias", domain alias name, targeted domain, enabled]
+        Expected format: ["domainalias", domain alias name, targeted domain,
+                          enabled]
 
         :param user: a ``User`` object
         :param row: a list containing the alias definition
@@ -94,4 +94,5 @@ class DomainAlias(AdminObject):
         csvwriter.writerow(["domainalias", self.name,
                             self.target.name, self.enabled])
 
+
 reversion.register(DomainAlias)
diff --git a/modoboa/admin/models/mailbox.py b/modoboa/admin/models/mailbox.py
index d32005959..610157536 100644
--- a/modoboa/admin/models/mailbox.py
+++ b/modoboa/admin/models/mailbox.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Models related to mailboxes management."""
 
 from __future__ import unicode_literals
@@ -5,6 +7,8 @@ from __future__ import unicode_literals
 import os
 import pwd
 
+from reversion import revisions as reversion
+
 from django.contrib.contenttypes.models import ContentType
 from django.db import models
 from django.db.models import Q
@@ -12,14 +16,11 @@ from django.db.models.manager import Manager
 from django.utils.encoding import python_2_unicode_compatible, smart_text
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from reversion import revisions as reversion
-
 from modoboa.core.models import User
 from modoboa.lib import exceptions as lib_exceptions
 from modoboa.lib.email_utils import split_mailbox
 from modoboa.lib.sysutils import exec_cmd
 from modoboa.parameters import tools as param_tools
-
 from .base import AdminObject
 from .domain import Domain
 
@@ -42,7 +43,7 @@ class Quota(models.Model):
     """Keeps track of Mailbox current quota."""
 
     username = models.EmailField(primary_key=True, max_length=254)
-    bytes = models.BigIntegerField(default=0)
+    bytes = models.BigIntegerField(default=0)  # NOQA:A003
     messages = models.IntegerField(default=0)
 
     objects = QuotaManager()
@@ -66,9 +67,9 @@ class MailboxManager(Manager):
         """
         qf = None
         if squery is not None:
-            if '@' in squery:
-                parts = squery.split('@')
-                addrfilter = '@'.join(parts[:-1])
+            if "@" in squery:
+                parts = squery.split("@")
+                addrfilter = "@".join(parts[:-1])
                 domfilter = parts[-1]
                 qf = (
                     Q(address__contains=addrfilter) &
@@ -81,7 +82,7 @@ class MailboxManager(Manager):
                 )
         ids = admin.objectaccess_set \
             .filter(content_type=ContentType.objects.get_for_model(Mailbox)) \
-            .values_list('object_id', flat=True)
+            .values_list("object_id", flat=True)
         if qf is not None:
             qf = Q(pk__in=ids) & qf
         else:
@@ -94,7 +95,7 @@ class Mailbox(AdminObject):
     """User mailbox."""
 
     address = models.CharField(
-        ugettext_lazy('address'), max_length=252,
+        ugettext_lazy("address"), max_length=252,
         help_text=ugettext_lazy(
             "Mailbox address (without the @domain.tld part)")
     )
@@ -375,8 +376,8 @@ class MailboxOperation(models.Model):
 
     mailbox = models.ForeignKey(Mailbox, blank=True, null=True,
                                 on_delete=models.CASCADE)
-    type = models.CharField(
-        max_length=20, choices=(('rename', 'rename'), ('delete', 'delete'))
+    type = models.CharField(  # NOQA:A003
+        max_length=20, choices=(("rename", "rename"), ("delete", "delete"))
     )
     argument = models.TextField()
 
@@ -384,6 +385,6 @@ class MailboxOperation(models.Model):
         app_label = "admin"
 
     def __str__(self):
-        if self.type == 'rename':
-            return 'Rename %s -> %s' % (self.argument, self.mailbox.mail_home)
-        return 'Delete %s' % self.argument
+        if self.type == "rename":
+            return "Rename %s -> %s" % (self.argument, self.mailbox.mail_home)
+        return "Delete %s" % self.argument
diff --git a/modoboa/admin/models/mxrecord.py b/modoboa/admin/models/mxrecord.py
index 4a4f71e5b..3d2cf9de8 100644
--- a/modoboa/admin/models/mxrecord.py
+++ b/modoboa/admin/models/mxrecord.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """MX records storage."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/admin/postfix_maps.py b/modoboa/admin/postfix_maps.py
index c904a7eeb..62b84748c 100644
--- a/modoboa/admin/postfix_maps.py
+++ b/modoboa/admin/postfix_maps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Map file definitions for postfix."""
 
 from __future__ import unicode_literals
@@ -7,7 +9,7 @@ class DomainsMap(object):
 
     """Map to list all domains."""
 
-    filename = 'sql-domains.cf'
+    filename = "sql-domains.cf"
     mysql = (
         "SELECT name FROM admin_domain "
         "WHERE name='%s' AND type='domain' AND enabled=1"
@@ -26,7 +28,7 @@ class DomainsAliasesMap(object):
 
     """Map to list all domain aliases."""
 
-    filename = 'sql-domain-aliases.cf'
+    filename = "sql-domain-aliases.cf"
     mysql = (
         "SELECT dom.name FROM admin_domain dom "
         "INNER JOIN admin_domainalias domal ON dom.id=domal.target_id "
@@ -48,7 +50,7 @@ class AliasesMap(object):
 
     """A map to list all mailbox aliases."""
 
-    filename = 'sql-aliases.cf'
+    filename = "sql-aliases.cf"
     mysql = (
         "SELECT alr.address FROM modoboa_admin_aliasrecipient AS alr "
         "INNER JOIN admin_alias AS al ON alr.alias_id=al.id "
@@ -73,7 +75,7 @@ class MaintainMap(object):
 
     """Map files to list non available mailboxes."""
 
-    filename = 'sql-maintain.cf'
+    filename = "sql-maintain.cf"
     mysql = (
         "SELECT '450 Requested mail action not taken: mailbox unavailable' "
         "FROM admin_mailbox mb INNER JOIN admin_domain dom "
diff --git a/modoboa/admin/serializers.py b/modoboa/admin/serializers.py
index 4d28233da..d5e2ac88c 100644
--- a/modoboa/admin/serializers.py
+++ b/modoboa/admin/serializers.py
@@ -1,27 +1,28 @@
+# -*- coding: utf-8 -*-
+
 """Admin serializers."""
 
 from __future__ import unicode_literals
 
 from django.conf import settings
+from django.contrib.auth import password_validation
 from django.core.exceptions import ValidationError
 from django.shortcuts import get_object_or_404
-from django.utils.translation import ugettext as _, ugettext_lazy
 from django.utils.encoding import force_text
-
-from django.contrib.auth import password_validation
+from django.utils.translation import ugettext as _, ugettext_lazy
 
 from rest_framework import serializers
 
 from modoboa.admin import models as admin_models
-from modoboa.core import constants as core_constants
-from modoboa.core import models as core_models
-from modoboa.core import signals as core_signals
-from modoboa.lib import exceptions as lib_exceptions
-from modoboa.lib import permissions, email_utils, fields as lib_fields
+from modoboa.core import (
+    constants as core_constants, models as core_models, signals as core_signals
+)
+from modoboa.lib import (
+    email_utils, exceptions as lib_exceptions, fields as lib_fields,
+    permissions
+)
 from modoboa.parameters import tools as param_tools
-
-from . import lib
-from . import models
+from . import lib, models
 
 
 class DomainSerializer(serializers.ModelSerializer):
@@ -32,7 +33,10 @@ class DomainSerializer(serializers.ModelSerializer):
         model = models.Domain
         fields = (
             "pk", "name", "quota", "default_mailbox_quota", "enabled", "type",
+            "enable_dkim", "dkim_key_selector", "dkim_key_length",
+            "dkim_public_key"
         )
+        read_only_fields = ("pk", "dkim_public_key", )
 
     def validate_name(self, value):
         """Check name constraints."""
@@ -62,8 +66,8 @@ class DomainSerializer(serializers.ModelSerializer):
         domain = models.Domain(**validated_data)
         creator = self.context["request"].user
         core_signals.can_create_object.send(
-                sender=self.__class__, context=creator,
-                klass=models.Domain, instance=domain)
+            sender=self.__class__, context=creator,
+            klass=models.Domain, instance=domain)
         domain.save(creator=creator)
         return domain
 
diff --git a/modoboa/admin/signals.py b/modoboa/admin/signals.py
index facb879b9..b085d7807 100644
--- a/modoboa/admin/signals.py
+++ b/modoboa/admin/signals.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa admin signals."""
 
 from __future__ import unicode_literals
@@ -30,3 +32,4 @@ get_domain_form_instances = django.dispatch.Signal(
 # get_domain_tags = django.dispatch.Signal(providing_args=["domain"])
 import_object = django.dispatch.Signal(providing_args=["objtype"])
 use_external_recipients = django.dispatch.Signal(providing_args=["recipients"])
+new_dkim_keys = django.dispatch.Signal(providing_args=["domains"])
diff --git a/modoboa/admin/static/admin/js/admin.js b/modoboa/admin/static/admin/js/admin.js
index b198b9ab7..3db83f02f 100644
--- a/modoboa/admin/static/admin/js/admin.js
+++ b/modoboa/admin/static/admin/js/admin.js
@@ -161,6 +161,24 @@ Domains.prototype = {
         $(document).trigger('domain_listing_refresh');
     },
 
+    /**
+     * Add a type to let the server know what kind of object we expect.
+     *
+     * @this Listing
+     */
+    get_load_page_args: function() {
+        var args = Admin.prototype.get_load_page_args.call(this);
+
+        if (this.navobj.getbaseurl() === "list") {
+            args.objtype = "domain";
+            this.options.eor_message = gettext("No more domain to show");
+        } else {
+            args.objtype = "quota";
+            this.options.eor_message = gettext("No more quota to show");
+        }
+        return args;
+    },
+
     /**
      * Navigation callback: default.
      *
@@ -305,6 +323,7 @@ Domains.prototype = {
             },
             success_callback: $.proxy(this.reload_listing, this)
         });
+        $(document).trigger('domwizard_init');
     },
 
     domainform_cb: function() {
diff --git a/modoboa/admin/templates/admin/_domain_dkim_key.html b/modoboa/admin/templates/admin/_domain_dkim_key.html
index d867ac509..ae71983e3 100644
--- a/modoboa/admin/templates/admin/_domain_dkim_key.html
+++ b/modoboa/admin/templates/admin/_domain_dkim_key.html
@@ -1,6 +1,6 @@
 {% load i18n %}
 
-<div class="modal-dialog {% block modal_css_classes %}{% endblock %}">
+<div class="modal-dialog modal-lg">
   <div class="modal-content">
     <div class="modal-header">
       <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">{% trans "Close" %}</span></button>
@@ -13,7 +13,7 @@
       </div>
       <div class="alert alert-info" style="overflow-wrap: break-word;">
         <strong>{% trans "Bind/named format" %}</strong><br>
-        {{ domain.bind_format_dkim_public_key }}
+        <span style="white-space: pre">{{ domain.bind_format_dkim_public_key }}</span>
       </div>
     </div>
     <div class="modal-footer">
diff --git a/modoboa/admin/templates/admin/domains.html b/modoboa/admin/templates/admin/domains.html
index 10f18baa6..5d354d6bd 100644
--- a/modoboa/admin/templates/admin/domains.html
+++ b/modoboa/admin/templates/admin/domains.html
@@ -15,7 +15,7 @@
   <script type="text/javascript">
    $(document).ready(function() {
        admin = new Domains({
-           load_page_url: "{% url 'admin:_domain_list' %}"
+           load_page_url: "{% url 'admin:domain_page' %}"
        });
    });
   </script>
diff --git a/modoboa/admin/templatetags/__init__.py b/modoboa/admin/templatetags/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/admin/templatetags/__init__.py
+++ b/modoboa/admin/templatetags/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/admin/templatetags/admin_tags.py b/modoboa/admin/templatetags/admin_tags.py
index 202088157..038eddb21 100644
--- a/modoboa/admin/templatetags/admin_tags.py
+++ b/modoboa/admin/templatetags/admin_tags.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Admin extension tags."""
 
 from __future__ import unicode_literals
@@ -5,15 +7,14 @@ from __future__ import unicode_literals
 from functools import reduce
 
 from django import template
-from django.urls import reverse
 from django.template.loader import render_to_string
+from django.urls import reverse
 from django.utils.safestring import mark_safe
 from django.utils.translation import ugettext as _, ugettext_lazy
 
 from modoboa.core import signals as core_signals
 from modoboa.lib.templatetags.lib_tags import render_link
 from modoboa.lib.web_utils import render_actions
-
 from .. import signals
 
 register = template.Library()
@@ -75,7 +76,7 @@ def domains_menu(selection, user, ajax_mode=True):
              "modalcb": "admin.exportform_cb"}
         ]
 
-    return render_to_string('common/menulist.html', {
+    return render_to_string("common/menulist.html", {
         "entries": entries,
         "selection": selection,
         "user": user
@@ -123,7 +124,7 @@ def identities_menu(user, selection=None, ajax_mode=True):
          "modalcb": "admin.exportform_cb"}
     ]
 
-    return render_to_string('common/menulist.html', {
+    return render_to_string("common/menulist.html", {
         "entries": entries,
         "user": user
     })
@@ -157,7 +158,7 @@ def domain_actions(user, domain):
 
     responses = signals.extra_domain_actions.send(
         sender=None, user=user, domain=domain)
-    for receiver, response in responses:
+    for _receiver, response in responses:
         if response:
             actions += response
 
@@ -229,15 +230,15 @@ def domain_aliases(domain):
     :rtype: str
     """
     if not domain.aliases.count():
-        return '---'
-    res = ''
+        return "---"
+    res = ""
     for alias in domain.aliases.all():
-        res += '%s<br/>' % alias.name
+        res += "%s<br/>" % alias.name
     return mark_safe(res)
 
 
 @register.simple_tag
-def identity_modify_link(identity, active_tab='default'):
+def identity_modify_link(identity, active_tab="default"):
     """Return the appropriate modification link.
 
     According to the identity type, a specific modification link (URL)
diff --git a/modoboa/admin/tests/__init__.py b/modoboa/admin/tests/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/admin/tests/__init__.py
+++ b/modoboa/admin/tests/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/admin/tests/dovecot b/modoboa/admin/tests/dovecot
index dbb210754..66b2424a1 100755
--- a/modoboa/admin/tests/dovecot
+++ b/modoboa/admin/tests/dovecot
@@ -1,3 +1,3 @@
-#!/bin/bash
+#!/bin/sh
 
 echo "2.12"
diff --git a/modoboa/admin/tests/test_account.py b/modoboa/admin/tests/test_account.py
index cddbe6297..ead26e6a1 100644
--- a/modoboa/admin/tests/test_account.py
+++ b/modoboa/admin/tests/test_account.py
@@ -1,34 +1,31 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
 from unittest import skipIf
 
-from django.urls import reverse
 from django.test import override_settings
+from django.urls import reverse
 
 from modoboa.core import factories as core_factories
-from modoboa.core.tests import test_ldap
 from modoboa.core.models import User
-from modoboa.lib.tests import ModoTestCase
-from modoboa.lib.tests import NO_LDAP
+from modoboa.core.tests import test_ldap
+from modoboa.lib.tests import NO_LDAP, ModoTestCase
 from modoboa.limits import utils as limits_utils
-
-from .. import factories
-from .. import models
+from .. import factories, models
 
 
 class AuthenticationTestCase(ModoTestCase):
     """Check authentication."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AuthenticationTestCase, cls).setUpTestData()
         cls.mb = factories.MailboxFactory(
             domain__name="test.com", address="user",
             user__username="user@test.com",
-            user__groups=('SimpleUsers',)
+            user__groups=("SimpleUsers",)
         )
 
     def test_authentication_unicode(self):
@@ -46,18 +43,18 @@ class AuthenticationTestCase(ModoTestCase):
 class AccountTestCase(ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AccountTestCase, cls).setUpTestData()
         factories.populate_database()
 
     def test_crud(self):
-        values = dict(
-            username="tester@test.com", first_name="Tester", last_name="Toto",
-            password1="Toto1234", password2="Toto1234", role="SimpleUsers",
-            quota_act=True,
-            is_active=True, email="tester@test.com", stepid='step2'
-        )
+        values = {
+            "username": "tester@test.com", "first_name": "Tester",
+            "last_name": "Toto", "password1": "Toto1234",
+            "password2": "Toto1234", "role": "SimpleUsers", "quota_act": True,
+            "is_active": True, "email": "tester@test.com", "stepid": "step2"
+        }
         self.ajax_post(reverse("admin:account_add"), values)
 
         account = User.objects.get(username="tester@test.com")
@@ -344,12 +341,12 @@ class AccountTestCase(ModoTestCase):
 
     def test_utf8_username(self):
         """Create an account with non-ASCII characters."""
-        values = dict(
-            username="téster@test.com", first_name="Tester", last_name="Toto",
-            password1="Toto1234", password2="Toto1234", role="SimpleUsers",
-            quota_act=True,
-            is_active=True, email="téster@test.com", stepid="step2"
-        )
+        values = {
+            "username": "téster@test.com", "first_name": "Tester",
+            "last_name": "Toto", "password1": "Toto1234",
+            "password2": "Toto1234", "role": "SimpleUsers", "quota_act": True,
+            "is_active": True, "email": "téster@test.com", "stepid": "step2"
+        }
         self.ajax_post(reverse("admin:account_add"), values)
 
     def _set_quota(self, email, value, expected_status=200):
@@ -459,8 +456,8 @@ class AccountTestCase(ModoTestCase):
 
 @skipIf(NO_LDAP, "No ldap module installed")
 @override_settings(AUTHENTICATION_BACKENDS=(
-    'modoboa.lib.authbackends.LDAPBackend',
-    'django.contrib.auth.backends.ModelBackend',
+    "modoboa.lib.authbackends.LDAPBackend",
+    "django.contrib.auth.backends.ModelBackend",
 ))
 class LDAPAccountTestCase(test_ldap.LDAPTestCaseMixin, ModoTestCase):
     """Check LDAP related code."""
@@ -481,11 +478,11 @@ class LDAPAccountTestCase(test_ldap.LDAPTestCaseMixin, ModoTestCase):
 class PermissionsTestCase(ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(PermissionsTestCase, cls).setUpTestData()
         parameters = {}
-        for name, tpl in limits_utils.get_user_limit_templates():
+        for name, _definition in limits_utils.get_user_limit_templates():
             parameters["deflt_user_{0}_limit".format(name)] = 2
         cls.localconfig.parameters.set_values(parameters, app="limits")
         cls.localconfig.save()
@@ -597,7 +594,7 @@ class PermissionsTestCase(ModoTestCase):
 
         response = self.client.get(
             reverse("admin:account_change", args=[self.user.id]),
-            HTTP_X_REQUESTED_WITH='XMLHttpRequest')
+            HTTP_X_REQUESTED_WITH="XMLHttpRequest")
         self.assertNotEqual(response["Content-Type"], "application/json")
 
     def test_domainadmin_deletes_superadmin(self):
@@ -607,12 +604,12 @@ class PermissionsTestCase(ModoTestCase):
         for the associated domain, this domain admin must not be able
         to access the super admin.
         """
-        values = dict(
-            username="superadmin2@test.com", first_name="Super",
-            last_name="Admin", password1="Toto1234", password2="Toto1234",
-            role="SuperAdmins", is_active=True,
-            email="superadmin2@test.com", stepid='step2'
-        )
+        values = {
+            "username": "superadmin2@test.com", "first_name": "Super",
+            "last_name": "Admin", "password1": "Toto1234",
+            "password2": "Toto1234", "role": "SuperAdmins", "is_active": True,
+            "email": "superadmin2@test.com", "stepid": "step2"
+        }
         self.ajax_post(
             reverse("admin:account_add"),
             values
@@ -627,22 +624,22 @@ class PermissionsTestCase(ModoTestCase):
     def test_domainadmin_dlist_local_domain_not_owned(self):
         """Check if a domain admin can use a local mailbox he can't
         access as a recipient in a distribution list"""
-        values = dict(
-            address="all@test.com",
-            recipients="user@test.com",
-            recipients_1="user@test2.com",
-            enabled=True
-        )
+        values = {
+            "address": "all@test.com",
+            "recipients": "user@test.com",
+            "recipients_1": "user@test2.com",
+            "enabled": True
+        }
         self.ajax_post(reverse("admin:alias_add"), values)
 
     def test_domainadmin_master_user(self):
         """Check domain administrator is not allowed to access this feature."""
-        values = dict(
-            username="user10@test.com", first_name="Test",
-            last_name="Test", password1="Toto1234", password2="Toto1234",
-            role="SimpleUsers", is_active=True, master_user=True,
-            email="user10@test.com", stepid='step2'
-        )
+        values = {
+            "username": "user10@test.com", "first_name": "Test",
+            "last_name": "Test", "password1": "Toto1234",
+            "password2": "Toto1234", "role": "SimpleUsers", "is_active": True,
+            "master_user": True, "email": "user10@test.com", "stepid": "step2"
+        }
         self.ajax_post(
             reverse("admin:account_add"),
             values, status=400
@@ -656,7 +653,7 @@ class PermissionsTestCase(ModoTestCase):
         dom = models.Domain.objects.get(name="test.com")
         mb = factories.MailboxFactory(
             domain=dom, address="admin2",
-            user__username="admin2@test.com", user__groups=('DomainAdmins', ),
+            user__username="admin2@test.com", user__groups=("DomainAdmins", ),
             user__password="{PLAIN}toto")
         dom.add_admin(mb.user)
         self.client.logout()
diff --git a/modoboa/admin/tests/test_alias.py b/modoboa/admin/tests/test_alias.py
index 3df90621d..b79ed39b6 100644
--- a/modoboa/admin/tests/test_alias.py
+++ b/modoboa/admin/tests/test_alias.py
@@ -1,34 +1,33 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
-"""Admin test cases."""
-
 from django.urls import reverse
 
 from modoboa.core.models import User
 from modoboa.lib.tests import ModoTestCase
-
 from .. import factories
 from ..models import Alias, AliasRecipient, Domain
 
+"""Admin test cases."""
+
 
 class AliasTestCase(ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AliasTestCase, cls).setUpTestData()
         factories.populate_database()
 
     def test_alias(self):
         user = User.objects.get(username="user@test.com")
-        values = dict(
-            username="user@test.com", role=user.role,
-            is_active=user.is_active, email="user@test.com",
-            aliases="toto@test.com", aliases_1="titi@test.com",
-            language="en"
-        )
+        values = {
+            "username": "user@test.com", "role": user.role,
+            "is_active": user.is_active, "email": "user@test.com",
+            "aliases": "toto@test.com", "aliases_1": "titi@test.com",
+            "language": "en"
+        }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
@@ -66,11 +65,11 @@ class AliasTestCase(ModoTestCase):
     def test_upper_case_alias(self):
         """Try to create an upper case alias."""
         user = User.objects.get(username="user@test.com")
-        values = dict(
-            username="user@test.com", role=user.role,
-            is_active=user.is_active, email="user@test.com",
-            aliases="Toto@test.com", language="en"
-        )
+        values = {
+            "username": "user@test.com", "role": user.role,
+            "is_active": user.is_active, "email": "user@test.com",
+            "aliases": "Toto@test.com", "language": "en"
+        }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
@@ -96,11 +95,11 @@ class AliasTestCase(ModoTestCase):
     def test_append_alias_with_tag(self):
         """Try to create a alias with tag in recipient address"""
         user = User.objects.get(username="user@test.com")
-        values = dict(
-            username="user@test.com", role=user.role,
-            is_active=user.is_active, email="user@test.com",
-            language="en"
-        )
+        values = {
+            "username": "user@test.com", "role": user.role,
+            "is_active": user.is_active, "email": "user@test.com",
+            "language": "en"
+        }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
@@ -120,11 +119,13 @@ class AliasTestCase(ModoTestCase):
 
     def test_utf8_alias(self):
         """Test alias with non-ASCII characters."""
-        values = dict(address="testé@test.com",
-                      recipients="user@test.com",
-                      recipients_1="admin@test.com",
-                      recipients_2="ext@titi.com",
-                      enabled=True)
+        values = {
+            "address": "testé@test.com",
+            "recipients": "user@test.com",
+            "recipients_1": "admin@test.com",
+            "recipients_2": "ext@titi.com",
+            "enabled": True
+        }
         self.ajax_post(
             reverse("admin:alias_add"), values
         )
@@ -168,7 +169,7 @@ class AliasTestCase(ModoTestCase):
             Alias.DoesNotExist, Alias.objects.get, address="all@test.com")
 
     def test_forward(self):
-        values = dict(address="forward2@test.com", recipients="rcpt@dest.com")
+        values = {"address": "forward2@test.com", "recipients": "rcpt@dest.com"}
         self.ajax_post(
             reverse("admin:alias_add"), values
         )
@@ -191,7 +192,7 @@ class AliasTestCase(ModoTestCase):
             Alias.DoesNotExist, Alias.objects.get, address="forward2@test.com")
 
     def test_forward_and_local_copies(self):
-        values = dict(address="user@test.com", recipients="rcpt@dest.com")
+        values = {"address": "user@test.com", "recipients": "rcpt@dest.com"}
         self.ajax_post(
             reverse("admin:alias_add"), values
         )
@@ -242,21 +243,23 @@ class AliasTestCase(ModoTestCase):
            changed.
 
         """
-        values = dict(address="list@test.com",
-                      recipients="user@test.com",
-                      recipients_1="admin@test.com",
-                      enabled=True)
+        values = {
+            "address": "list@test.com",
+            "recipients": "user@test.com",
+            "recipients_1": "admin@test.com",
+            "enabled": True
+        }
         self.ajax_post(
             reverse("admin:alias_add"), values
         )
 
         user = User.objects.get(username="user@test.com")
-        values = dict(
-            username=user.username, first_name="Tester", last_name="Toto",
-            password1="Toto1234", password2="Toto1234", role="SimpleUsers",
-            quota_act=True, is_active=True, email=user.email,
-            language="en"
-        )
+        values = {
+            "username": user.username, "first_name": "Tester",
+            "last_name": "Toto", "password1": "Toto1234",
+            "password2": "Toto1234", "role": "SimpleUsers", "quota_act": True,
+            "is_active": True, "email": user.email, "language": "en"
+        }
         self.ajax_post(reverse("admin:account_change", args=[user.id]), values)
 
         self.assertEqual(
@@ -277,12 +280,12 @@ class AliasTestCase(ModoTestCase):
         self.client.force_login(admin)
 
         user = User.objects.get(username="user@test.com")
-        values = dict(
-            username="user@test.com", role=user.role,
-            is_active=user.is_active, email="user@test.com",
-            aliases="toto@test.com", aliases_1="titi@test2.com",
-            language="en"
-        )
+        values = {
+            "username": "user@test.com", "role": user.role,
+            "is_active": user.is_active, "email": "user@test.com",
+            "aliases": "toto@test.com", "aliases_1": "titi@test2.com",
+            "language": "en"
+        }
         response = self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values, 400
diff --git a/modoboa/admin/tests/test_api.py b/modoboa/admin/tests/test_api.py
index bd5c2582c..c32260ead 100644
--- a/modoboa/admin/tests/test_api.py
+++ b/modoboa/admin/tests/test_api.py
@@ -8,7 +8,6 @@ import copy
 import json
 
 import dns.resolver
-from mock import patch
 
 from django.test import override_settings
 from django.urls import reverse
@@ -16,20 +15,24 @@ from django.urls import reverse
 from rest_framework.authtoken.models import Token
 
 from modoboa.admin import models as admin_models
-from modoboa.core import factories as core_factories
-from modoboa.core import models as core_models
+from modoboa.core import factories as core_factories, models as core_models
 from modoboa.lib.tests import ModoAPITestCase
-
 from . import utils
-from .. import factories
-from .. import models
+from .. import factories, models
+
+try:
+    # mock is part of the Python (>= 3.3) standard library
+    from unittest import mock
+except ImportError:
+    # fall back to the mock backport
+    import mock
 
 
 class DomainAPITestCase(ModoAPITestCase):
     """Check API."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DomainAPITestCase, cls).setUpTestData()
         factories.populate_database()
@@ -69,13 +72,13 @@ class DomainAPITestCase(ModoAPITestCase):
         self.assertIn("default_mailbox_quota", response.data)
 
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
         response = self.client.post(
             url, {"name": "test4.com", "default_mailbox_quota": 10})
         self.assertEqual(response.status_code, 403)
 
-    @patch.object(dns.resolver.Resolver, "query")
-    @patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("socket.getaddrinfo")
     def test_create_domain_with_mx_check(self, mock_getaddrinfo, mock_query):
         """Check domain creation when MX check is activated."""
         self.set_global_parameter("enable_admin_limits", False, app="limits")
@@ -84,7 +87,7 @@ class DomainAPITestCase(ModoAPITestCase):
         reseller = core_factories.UserFactory(
             username="reseller", groups=("Resellers", ))
         token = Token.objects.create(user=reseller)
-        self.client.credentials(HTTP_AUTHORIZATION='Token ' + token.key)
+        self.client.credentials(HTTP_AUTHORIZATION="Token " + token.key)
 
         url = reverse("api:domain-list")
         mock_query.side_effect = utils.mock_dns_query_result
@@ -140,7 +143,7 @@ class DomainAliasAPITestCase(ModoAPITestCase):
     """Check DomainAlias API."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DomainAliasAPITestCase, cls).setUpTestData()
         factories.populate_database()
@@ -169,7 +172,7 @@ class DomainAliasAPITestCase(ModoAPITestCase):
         self.assertEqual(len(response.data), 1)
 
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
         response = self.client.get(reverse("api:domain_alias-list"))
         self.assertEqual(response.status_code, 200)
         self.assertEqual(len(response.data), 0)
@@ -191,7 +194,7 @@ class DomainAliasAPITestCase(ModoAPITestCase):
         self.assertEqual(dalias.target, target)
 
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
         response = self.client.post(
             url, {"name": "dalias4.com", "target": target.pk}, format="json")
         self.assertEqual(response.status_code, 403)
@@ -234,7 +237,7 @@ class AccountAPITestCase(ModoAPITestCase):
     }
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AccountAPITestCase, cls).setUpTestData()
         factories.populate_database()
@@ -389,7 +392,7 @@ class AccountAPITestCase(ModoAPITestCase):
     def test_create_account_as_domadmin(self):
         """As DomainAdmin, try to create a new account."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
         data = copy.deepcopy(self.ACCOUNT_DATA)
         data["mailbox"]["quota"] = 1000
         url = reverse("api:account-list")
@@ -566,7 +569,7 @@ class AliasAPITestCase(ModoAPITestCase):
     }
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AliasAPITestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_value(
@@ -604,7 +607,7 @@ class AliasAPITestCase(ModoAPITestCase):
         response = self.client.post(url, self.ALIAS_DATA, format="json")
         self.assertEqual(response.status_code, 201)
 
-        alias = json.loads(response.content.decode('utf-8'))
+        alias = json.loads(response.content.decode("utf-8"))
         alias = models.Alias.objects.filter(pk=alias["pk"]).first()
         domadmin = core_models.User.objects.get(username="admin@test.com")
         self.assertTrue(domadmin.can_access(alias))
@@ -626,7 +629,7 @@ class AliasAPITestCase(ModoAPITestCase):
     def test_create_alias_as_domadmin(self):
         """As DomainAdmin, try to create a new alias."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
         url = reverse("api:alias-list")
         response = self.client.post(url, self.ALIAS_DATA, format="json")
         self.assertEqual(response.status_code, 201)
@@ -689,7 +692,7 @@ class SenderAddressAPITestCase(ModoAPITestCase):
     """Check SenderAddress API."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(SenderAddressAPITestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_value(
@@ -723,7 +726,7 @@ class SenderAddressAPITestCase(ModoAPITestCase):
         self.assertEqual(response.status_code, 201)
 
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
         data = {"address": "user@test2.com", "mailbox": mbox.pk}
         response = self.client.post(url, data)
         self.assertEqual(response.status_code, 400)
diff --git a/modoboa/admin/tests/test_data/import_domains.csv b/modoboa/admin/tests/test_data/import_domains.csv
new file mode 100644
index 000000000..d879f8a16
--- /dev/null
+++ b/modoboa/admin/tests/test_data/import_domains.csv
@@ -0,0 +1,2 @@
+domain;domain1.com;1000;100;True
+domain;dĂłmain2.com;2000;200;True
diff --git a/modoboa/admin/tests/test_data/import_domains_duplicates.csv b/modoboa/admin/tests/test_data/import_domains_duplicates.csv
new file mode 100644
index 000000000..c5395f364
--- /dev/null
+++ b/modoboa/admin/tests/test_data/import_domains_duplicates.csv
@@ -0,0 +1,3 @@
+domain;domain1.com;1000;100;True
+domain;dĂłmain2.com;2000;200;True
+domain;dĂłmain2.com;2000;200;True
diff --git a/modoboa/admin/tests/test_data/import_domains_iso8859.csv b/modoboa/admin/tests/test_data/import_domains_iso8859.csv
new file mode 100644
index 000000000..415a03e21
--- /dev/null
+++ b/modoboa/admin/tests/test_data/import_domains_iso8859.csv
@@ -0,0 +1,2 @@
+domain;domain1.com;1000;100;True
+domain;dómain2.com;2000;200;True
diff --git a/modoboa/admin/tests/test_domain.py b/modoboa/admin/tests/test_domain.py
index cabab25e3..ad985f323 100644
--- a/modoboa/admin/tests/test_domain.py
+++ b/modoboa/admin/tests/test_domain.py
@@ -9,7 +9,6 @@ import shutil
 import tempfile
 
 import dns.resolver
-from mock import patch
 from testfixtures import compare
 
 from django.core.management import call_command
@@ -20,17 +19,23 @@ from modoboa.core import factories as core_factories
 from modoboa.core.models import User
 from modoboa.core.tests.test_views import SETTINGS_SAMPLE
 from modoboa.lib.tests import ModoTestCase
-
 from . import utils
 from .. import factories
-from ..models import Domain, Alias
+from ..models import Alias, Domain
+
+try:
+    # mock is part of the Python (>= 3.3) standard library
+    from unittest import mock
+except ImportError:
+    # fall back to the mock backport
+    import mock
 
 
 class DomainTestCase(ModoTestCase):
     """Test case for Domain."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DomainTestCase, cls).setUpTestData()
         factories.populate_database()
@@ -176,7 +181,7 @@ class DomainTestCase(ModoTestCase):
         values = {
             "name": "pouet.com", "quota": 10, "default_mailbox_quota": 100,
             "create_dom_admin": True, "dom_admin_username": "toto",
-            "create_aliases": True, "type": "domain", "stepid": 'step3'
+            "create_aliases": True, "type": "domain", "stepid": "step3"
         }
         response = self.ajax_post(
             reverse("admin:domain_add"),
@@ -206,8 +211,8 @@ class DomainTestCase(ModoTestCase):
         self.assertContains(response, "value=\"500\"")
         self.assertContains(response, "value=\"50\"")
 
-    @patch.object(dns.resolver.Resolver, "query")
-    @patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("socket.getaddrinfo")
     def test_create_and_check_mx(self, mock_getaddrinfo, mock_query):
         """Check for authorized MX record."""
         reseller = core_factories.UserFactory(
@@ -347,22 +352,30 @@ class DomainTestCase(ModoTestCase):
         url = reverse("core:dashboard")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        self.assertIn("Global statistics", response.content.decode('utf-8'))
+        self.assertIn("Global statistics", response.content.decode("utf-8"))
 
         self.client.force_login(
             User.objects.get(username="admin@test.com"))
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        content = response.content.decode('utf-8')
+        content = response.content.decode("utf-8")
         self.assertNotIn("Global statistics", content)
         self.assertIn("Per-domain statistics", content)
 
+    def test_page_loader(self):
+        """Test page loader view."""
+        url = reverse("admin:domain_page")
+        response = self.ajax_get(url)
+        self.assertIn("handle_mailboxes", response)
+        response = self.ajax_get("{}?objtype=quota".format(url))
+        self.assertIn("progress-bar", response["rows"])
+
 
 class DKIMTestCase(ModoTestCase):
     """Test case for DKIM."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa: N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DKIMTestCase, cls).setUpTestData()
         factories.populate_database()
diff --git a/modoboa/admin/tests/test_domain_alias.py b/modoboa/admin/tests/test_domain_alias.py
index 5dd667702..d02e4ef96 100644
--- a/modoboa/admin/tests/test_domain_alias.py
+++ b/modoboa/admin/tests/test_domain_alias.py
@@ -1,23 +1,22 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
 from django.urls import reverse
 
 from modoboa.lib.tests import ModoTestCase
-
 from .. import factories
-from ..models import Domain, DomainAlias, Alias
+from ..models import Alias, Domain, DomainAlias
 
 
 class DomainAliasTestCase(ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DomainAliasTestCase, cls).setUpTestData()
         factories.populate_database()
-        cls.dom = Domain.objects.get(name='test.com')
+        cls.dom = Domain.objects.get(name="test.com")
 
     def test_model(self):
         dom = Domain.objects.get(name="test.com")
diff --git a/modoboa/admin/tests/test_export.py b/modoboa/admin/tests/test_export.py
index c48e3486d..686d9afc0 100644
--- a/modoboa/admin/tests/test_export.py
+++ b/modoboa/admin/tests/test_export.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Export related test cases."""
 
@@ -8,16 +8,14 @@ from django.urls import reverse
 from django.utils.encoding import force_text
 
 from modoboa.lib.tests import ModoTestCase
-
-from .. import factories
-from .. import models
+from .. import factories, models
 
 
 class ExportTestCase(ModoTestCase):
     """Test case for export operations."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(ExportTestCase, cls).setUpTestData()
         factories.populate_database()
@@ -40,7 +38,7 @@ class ExportTestCase(ModoTestCase):
             {"filename": "test.csv"}
         )
 
-    def assertListEqual(self, list1, list2):
+    def assertListEqual(self, list1, list2):  # NOQA:N802
         list1 = force_text(list1).split("\r\n")
         list2 = force_text(list2).split("\r\n")
         self.assertEqual(len(list1), len(list2))
@@ -67,7 +65,7 @@ class ExportTestCase(ModoTestCase):
     def test_export_identities(self):
         response = self.__export_identities()
         self.assertListEqual(
-            "account;admin@test.com;{PLAIN}toto;;;True;DomainAdmins;admin@test.com;10;test.com\r\naccount;admin@test2.com;{PLAIN}toto;;;True;DomainAdmins;admin@test2.com;10;test2.com\r\naccount;user@test.com;{PLAIN}toto;;;True;SimpleUsers;user@test.com;10\r\naccount;user@test2.com;{PLAIN}toto;;;True;SimpleUsers;user@test2.com;10\r\nalias;alias@test.com;True;user@test.com\r\nalias;forward@test.com;True;user@external.com\r\nalias;postmaster@test.com;True;test@truc.fr;toto@titi.com\r\n",
+            "account;admin@test.com;{PLAIN}toto;;;True;DomainAdmins;admin@test.com;10;test.com\r\naccount;admin@test2.com;{PLAIN}toto;;;True;DomainAdmins;admin@test2.com;10;test2.com\r\naccount;user@test.com;{PLAIN}toto;;;True;SimpleUsers;user@test.com;10\r\naccount;user@test2.com;{PLAIN}toto;;;True;SimpleUsers;user@test2.com;10\r\nalias;alias@test.com;True;user@test.com\r\nalias;forward@test.com;True;user@external.com\r\nalias;postmaster@test.com;True;test@truc.fr;toto@titi.com\r\n",  # NOQA:E501
             response.content.strip()
         )
 
@@ -81,7 +79,7 @@ class ExportTestCase(ModoTestCase):
             idtfilter="account", grpfilter="SimpleUsers"
         )
         self.assertListEqual(
-            "account;user@test.com;{PLAIN}toto;;;True;SimpleUsers;user@test.com;10\r\naccount;user@test2.com;{PLAIN}toto;;;True;SimpleUsers;user@test2.com;10\r\naccount;toto@test.com;{PLAIN}toto;LĂ©on;;True;SimpleUsers;toto@test.com;10",
+            "account;user@test.com;{PLAIN}toto;;;True;SimpleUsers;user@test.com;10\r\naccount;user@test2.com;{PLAIN}toto;;;True;SimpleUsers;user@test2.com;10\r\naccount;toto@test.com;{PLAIN}toto;LĂ©on;;True;SimpleUsers;toto@test.com;10",  # NOQA:E501
             response.content.strip()
         )
 
@@ -105,7 +103,7 @@ class ExportTestCase(ModoTestCase):
             idtfilter="account", grpfilter="DomainAdmins"
         )
         self.assertListEqual(
-            "account;admin@test.com;{PLAIN}toto;;;True;DomainAdmins;admin@test.com;10;test.com\r\naccount;admin@test2.com;{PLAIN}toto;;;True;DomainAdmins;admin@test2.com;10;test2.com",
+            "account;admin@test.com;{PLAIN}toto;;;True;DomainAdmins;admin@test.com;10;test.com\r\naccount;admin@test2.com;{PLAIN}toto;;;True;DomainAdmins;admin@test2.com;10;test2.com",  # NOQA:E501
             response.content.strip()
         )
 
@@ -113,5 +111,5 @@ class ExportTestCase(ModoTestCase):
         response = self.__export_identities(idtfilter="alias")
         self.assertEqual(
             response.content.decode().strip(),
-            "alias;alias@test.com;True;user@test.com\r\nalias;forward@test.com;True;user@external.com\r\nalias;postmaster@test.com;True;test@truc.fr;toto@titi.com"
+            "alias;alias@test.com;True;user@test.com\r\nalias;forward@test.com;True;user@external.com\r\nalias;postmaster@test.com;True;test@truc.fr;toto@titi.com"  # NOQA:E501
         )
diff --git a/modoboa/admin/tests/test_import_.py b/modoboa/admin/tests/test_import_.py
index cfe9f7317..aa0a5eaad 100644
--- a/modoboa/admin/tests/test_import_.py
+++ b/modoboa/admin/tests/test_import_.py
@@ -2,25 +2,34 @@
 
 from __future__ import unicode_literals
 
+import os
+
 import dns.resolver
-from mock import patch
 
 from django.core.files.base import ContentFile
+from django.core.management import call_command
+from django.core.management.base import CommandError
 from django.urls import reverse
 
 from modoboa.core import factories as core_factories
 from modoboa.core.models import User
 from modoboa.lib.tests import ModoTestCase
-
 from . import utils
 from .. import factories
-from ..models import Domain, Alias, DomainAlias
+from ..models import Alias, Domain, DomainAlias
+
+try:
+    # mock is part of the Python (>= 3.3) standard library
+    from unittest import mock
+except ImportError:
+    # fall back to the mock backport
+    import mock
 
 
 class ImportTestCase(ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):  # noqa:N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(ImportTestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_value(
@@ -79,8 +88,8 @@ domainalias; domalias1.com; domain1.com; True
             response,
             "Default mailbox quota cannot be greater than domain quota")
 
-    @patch.object(dns.resolver.Resolver, "query")
-    @patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("socket.getaddrinfo")
     def test_domain_import_with_mx_check(self, mock_getaddrinfo, mock_query):
         """Check domain import when MX check is enabled."""
         reseller = core_factories.UserFactory(
@@ -135,7 +144,7 @@ alias; alias1@test.com; True; user1@test.com
 forward; alias2@test.com; True; user1+ext@test.com
 forward; fwd1@test.com; True; user@extdomain.com
 dlist; dlist@test.com; True; user1@test.com; user@extdomain.com
-""", name="identities.csv")
+""", name="identities.csv")  # NOQA:E501
         self.client.post(
             reverse("admin:identity_import"),
             {"sourcefile": f, "crypt_password": True}
@@ -201,7 +210,7 @@ dlist; dlist@test.com; True; user1@test.com; user@extdomain.com
         """Try to import an account for nonlocal domain."""
         f = ContentFile(b"""
 account; user1@nonlocal.com; toto; User; One; True; SimpleUsers; user1@nonlocal.com; 0
-""", name="identities.csv")
+""", name="identities.csv")  # NOQA:E501
         self.client.post(
             reverse("admin:identity_import"),
             {"sourcefile": f, "crypt_password": True}
@@ -212,12 +221,12 @@ account; user1@nonlocal.com; toto; User; One; True; SimpleUsers; user1@nonlocal.
     def test_import_invalid_quota(self):
         f = ContentFile(b"""
 account; user1@test.com; toto; User; One; True; SimpleUsers; user1@test.com; ; test.com
-""", name="identities.csv")
+""", name="identities.csv")  # NOQA:E501
         resp = self.client.post(
             reverse("admin:identity_import"),
             {"sourcefile": f, "crypt_password": True}
         )
-        self.assertIn('wrong quota value', resp.content.decode())
+        self.assertIn("wrong quota value", resp.content.decode())
 
     def test_import_domain_by_domainadmin(self):
         """Check if a domain admin is not allowed to import a domain."""
@@ -230,7 +239,9 @@ domain; domain2.com; 1000; 200; False
             reverse("admin:identity_import"),
             {"sourcefile": f, "crypt_password": True}
         )
-        self.assertIn("You are not allowed to import domains", resp.content.decode())
+        self.assertIn(
+            "You are not allowed to import domains",
+            resp.content.decode())
         f = ContentFile(b"""
 domainalias; domalias1.com; test.com; True
 """, name="identities.csv")
@@ -239,7 +250,8 @@ domainalias; domalias1.com; test.com; True
             {"sourcefile": f, "crypt_password": True}
         )
         self.assertIn(
-            "You are not allowed to import domain aliases", resp.content.decode())
+            "You are not allowed to import domain aliases",
+            resp.content.decode())
 
     def test_import_quota_too_big(self):
         self.client.logout()
@@ -271,7 +283,7 @@ account; user1@test.com; toto; User; One; True; SimpleUsers; user1@test.com
         f = ContentFile("""
 account; admin@test.com; toto; Admin; ; True; DomainAdmins; admin@test.com; 0; test.com
 account; truc@test.com; toto; René; Truc; True; DomainAdmins; truc@test.com; 0; test.com
-""", name="identities.csv")
+""", name="identities.csv")  # NOQA:E501
         self.client.post(
             reverse("admin:identity_import"),
             {"sourcefile": f, "crypt_password": True,
@@ -292,7 +304,7 @@ account; truc@test.com; toto; René; Truc; True; DomainAdmins; truc@test.com; 0;
         )
         f = ContentFile(b"""
 account; sa@test.com; toto; Super; Admin; True; SuperAdmins; superadmin@test.com; 50
-""", name="identities.csv")
+""", name="identities.csv")  # NOQA:E501
         self.client.post(
             reverse("admin:identity_import"),
             {"sourcefile": f, "crypt_password": True,
@@ -345,3 +357,72 @@ dĂłmain; dĂłmÂŞin2.com; 1000; 100; True
         self.assertEqual(dom.default_mailbox_quota, 100)
         self.assertTrue(dom.enabled)
         self.assertTrue(admin.is_owner(dom))
+
+    def test_import_command_missing_file(self):
+        with mock.patch("os.path.isfile") as mock_isfile:
+            mock_isfile.return_value = False
+            with self.assertRaises(CommandError) as cm:
+                call_command("modo", "import", "test.csv")
+                ex_message = cm.exception.messages
+                self.assertEqual(ex_message, "File not found")
+
+    def test_import_command(self):
+        test_file = os.path.join(
+            os.path.dirname(__file__),
+            "test_data/import_domains.csv"
+        )
+        call_command("modo", "import", test_file)
+
+        admin = User.objects.get(username="admin")
+
+        dom = Domain.objects.get(name="domain1.com")
+        self.assertEqual(dom.quota, 1000)
+        self.assertEqual(dom.default_mailbox_quota, 100)
+        self.assertTrue(dom.enabled)
+        self.assertTrue(admin.is_owner(dom))
+
+        dom = Domain.objects.get(name="dĂłmain2.com")
+        self.assertEqual(dom.quota, 2000)
+        self.assertEqual(dom.default_mailbox_quota, 200)
+        self.assertTrue(dom.enabled)
+        self.assertTrue(admin.is_owner(dom))
+
+    def test_import_command_non_utf8(self):
+        test_file = os.path.join(
+            os.path.dirname(__file__),
+            "test_data/import_domains_iso8859.csv"
+        )
+        call_command("modo", "import", test_file)
+        dom = Domain.objects.get(name="dĂłmain2.com")
+        self.assertEqual(dom.quota, 2000)
+
+    def test_import_command_duplicates(self):
+        test_file = os.path.join(
+            os.path.dirname(__file__),
+            "test_data/import_domains_duplicates.csv"
+        )
+        with self.assertRaises(CommandError) as cm:
+            call_command("modo", "import", test_file)
+            ex_message = cm.exception.messages
+            self.assertTrue(ex_message.startswith("Object already exists: "))
+
+    def test_import_command_duplicates_continue(self):
+        test_file = os.path.join(
+            os.path.dirname(__file__),
+            "test_data/import_domains_duplicates.csv"
+        )
+        call_command("modo", "import", "--continue-if-exists", test_file)
+
+        admin = User.objects.get(username="admin")
+
+        dom = Domain.objects.get(name="domain1.com")
+        self.assertEqual(dom.quota, 1000)
+        self.assertEqual(dom.default_mailbox_quota, 100)
+        self.assertTrue(dom.enabled)
+        self.assertTrue(admin.is_owner(dom))
+
+        dom = Domain.objects.get(name="dĂłmain2.com")
+        self.assertEqual(dom.quota, 2000)
+        self.assertEqual(dom.default_mailbox_quota, 200)
+        self.assertTrue(dom.enabled)
+        self.assertTrue(admin.is_owner(dom))
diff --git a/modoboa/admin/tests/test_mailbox_operations.py b/modoboa/admin/tests/test_mailbox_operations.py
index 81c02de97..6e598bb57 100644
--- a/modoboa/admin/tests/test_mailbox_operations.py
+++ b/modoboa/admin/tests/test_mailbox_operations.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Management command tests."""
 
 from __future__ import unicode_literals
@@ -6,16 +8,19 @@ import os
 import shutil
 import tempfile
 
-import mock
-
 from django.core.management import call_command
-from django.urls import reverse
 from django.test import override_settings
+from django.urls import reverse
 
 from modoboa.lib.tests import ModoTestCase
+from .. import factories, models
 
-from .. import factories
-from .. import models
+try:
+    # mock is part of the Python (>= 3.3) standard library
+    from unittest import mock
+except ImportError:
+    # fall back to the mock backport
+    import mock
 
 
 @override_settings(
@@ -24,7 +29,7 @@ class MailboxOperationTestCase(ModoTestCase):
     """Test management command."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(MailboxOperationTestCase, cls).setUpTestData()
         factories.populate_database()
diff --git a/modoboa/admin/tests/test_mapfiles.py b/modoboa/admin/tests/test_mapfiles.py
index 1f0104681..1da822f04 100644
--- a/modoboa/admin/tests/test_mapfiles.py
+++ b/modoboa/admin/tests/test_mapfiles.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Test map files generation."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/admin/tests/test_mx.py b/modoboa/admin/tests/test_mx.py
index 55969f857..fea42ee53 100644
--- a/modoboa/admin/tests/test_mx.py
+++ b/modoboa/admin/tests/test_mx.py
@@ -5,29 +5,32 @@
 from __future__ import unicode_literals
 
 import dns.resolver
-from mock import patch
 from testfixtures import LogCapture
 
-from django.core import mail
-from django.core import management
+from django.core import mail, management
 from django.test import override_settings
 from django.urls import reverse
 from django.utils.translation import ugettext as _
 
 from modoboa.core import factories as core_factories
 from modoboa.lib.tests import ModoTestCase
-
 from . import utils
-from .. import factories
+from .. import factories, models
 from ..lib import get_domain_mx_list
-from .. import models
+
+try:
+    # mock is part of the Python (>= 3.3) standard library
+    from unittest import mock
+except ImportError:
+    # fall back to the mock backport
+    import mock
 
 
 class MXTestCase(ModoTestCase):
     """TestCase for DNSBL related features."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa:N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create some data."""
         super(MXTestCase, cls).setUpTestData()
         cls.domain = factories.DomainFactory(name="modoboa.org")
@@ -52,11 +55,11 @@ class MXTestCase(ModoTestCase):
         cls.localconfig.save()
         models.MXRecord.objects.all().delete()
 
-    @patch("gevent.socket.gethostbyname")
-    @patch("socket.getaddrinfo")
-    @patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("gevent.socket.gethostbyname")
+    @mock.patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
     def test_management_command(
-         self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
+            self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
         """Check that command works fine."""
         mock_query.side_effect = utils.mock_dns_query_result
         mock_getaddrinfo.side_effect = utils.mock_ip_query_result
@@ -80,11 +83,11 @@ class MXTestCase(ModoTestCase):
         qs = models.MXRecord.objects.filter(domain=self.domain)
         self.assertEqual(id_, qs[0].id)
 
-    @patch("gevent.socket.gethostbyname")
-    @patch("socket.getaddrinfo")
-    @patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("gevent.socket.gethostbyname")
+    @mock.patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
     def test_single_domain_update(
-         self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
+            self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
         """Update only one domain."""
         mock_query.side_effect = utils.mock_dns_query_result
         mock_getaddrinfo.side_effect = utils.mock_ip_query_result
@@ -105,8 +108,8 @@ class MXTestCase(ModoTestCase):
         management.call_command(
             "modo", "check_mx", "--domain", "toto.com")
 
-    @patch("socket.getaddrinfo")
-    @patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
     def test_get_domain_mx_list_logging(self, mock_query, mock_getaddrinfo):
         mock_query.side_effect = utils.mock_dns_query_result
         mock_getaddrinfo.side_effect = utils.mock_ip_query_result
@@ -133,7 +136,7 @@ class MXTestCase(ModoTestCase):
             ("modoboa.admin", "WARNING",
                 _("Invalid IP address format for %(domain)s; %(addr)s")
                 % {"domain": "bad-response.example.com", "addr": "BAD"}),
-            )
+        )
 
 
 @override_settings(DNSBL_PROVIDERS=["zen.spamhaus.org"])
@@ -141,7 +144,7 @@ class DNSBLTestCase(ModoTestCase):
     """TestCase for DNSBL related features."""
 
     @classmethod
-    def setUpTestData(cls):  # noqa:N802
+    def setUpTestData(cls):  # NOQA:N802
         """Create some data."""
         super(DNSBLTestCase, cls).setUpTestData()
         cls.domain = factories.DomainFactory(name="modoboa.org")
@@ -152,11 +155,11 @@ class DNSBLTestCase(ModoTestCase):
             name="modoboa.com", enable_dns_checks=False)
         models.DNSBLResult.objects.all().delete()
 
-    @patch("gevent.socket.gethostbyname")
-    @patch("socket.getaddrinfo")
-    @patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("gevent.socket.gethostbyname")
+    @mock.patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
     def test_management_command(
-         self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
+            self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
         """Check that command works fine."""
         mock_query.side_effect = utils.mock_dns_query_result
         mock_getaddrinfo.side_effect = utils.mock_ip_query_result
@@ -173,11 +176,11 @@ class DNSBLTestCase(ModoTestCase):
         self.assertFalse(self.domain.uses_a_reserved_tld)
         self.assertTrue(self.domain2.uses_a_reserved_tld)
 
-    @patch("gevent.socket.gethostbyname")
-    @patch("socket.getaddrinfo")
-    @patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("gevent.socket.gethostbyname")
+    @mock.patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
     def test_notifications(
-         self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
+            self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
         """Check notifications."""
         mock_query.side_effect = utils.mock_dns_query_result
         mock_getaddrinfo.side_effect = utils.mock_ip_query_result
@@ -189,11 +192,11 @@ class DNSBLTestCase(ModoTestCase):
                 print(message.subject)
         self.assertEqual(len(mail.outbox), 2)
 
-    @patch("gevent.socket.gethostbyname")
-    @patch("socket.getaddrinfo")
-    @patch.object(dns.resolver.Resolver, "query")
+    @mock.patch("gevent.socket.gethostbyname")
+    @mock.patch("socket.getaddrinfo")
+    @mock.patch.object(dns.resolver.Resolver, "query")
     def test_management_command_no_dnsbl(
-         self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
+            self, mock_query, mock_getaddrinfo, mock_g_gethostbyname):
         """Check that command works fine without dnsbl."""
         mock_query.side_effect = utils.mock_dns_query_result
         mock_getaddrinfo.side_effect = utils.mock_ip_query_result
diff --git a/modoboa/admin/tests/test_password_schemes.py b/modoboa/admin/tests/test_password_schemes.py
index 277d202b9..61b83b14a 100644
--- a/modoboa/admin/tests/test_password_schemes.py
+++ b/modoboa/admin/tests/test_password_schemes.py
@@ -1,28 +1,29 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from django.urls import reverse
 
 from modoboa.core.models import User
 from modoboa.lib.tests import ModoTestCase
-
 from .. import factories
 
 
 class PasswordSchemesTestCase(ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(PasswordSchemesTestCase, cls).setUpTestData()
         factories.populate_database()
 
     def _create_account(self):
-        values = dict(
-            username="tester@test.com", first_name="Tester", last_name="Toto",
-            password1="Toto1234", password2="Toto1234", role="SimpleUsers",
-            quota_act=True,
-            is_active=True, email="tester@test.com", stepid='step2'
-        )
+        values = {
+            "username": "tester@test.com", "first_name": "Tester",
+            "last_name": "Toto", "password1": "Toto1234",
+            "password2": "Toto1234", "role": "SimpleUsers", "quota_act": True,
+            "is_active": True, "email": "tester@test.com", "stepid": "step2"
+        }
         self.ajax_post(
             reverse("admin:account_add"),
             values
@@ -31,30 +32,30 @@ class PasswordSchemesTestCase(ModoTestCase):
     def _test_scheme(self, name, startpattern):
         self.set_global_parameter("password_scheme", name, app="core")
         self._create_account()
-        account = User.objects.get(username='tester@test.com')
+        account = User.objects.get(username="tester@test.com")
         self.assertTrue(account.password.startswith(startpattern))
-        self.assertTrue(account.check_password('Toto1234'))
+        self.assertTrue(account.check_password("Toto1234"))
 
     def test_bcrypt_scheme(self):
-        self._test_scheme('blfcrypt', '{BLF-CRYPT}')
+        self._test_scheme("blfcrypt", "{BLF-CRYPT}")
 
     def test_sha512crypt_scheme(self):
-        self._test_scheme('sha512crypt', '{SHA512-CRYPT}')
+        self._test_scheme("sha512crypt", "{SHA512-CRYPT}")
 
     def test_sha256crypt_scheme(self):
-        self._test_scheme('sha256crypt', '{SHA256-CRYPT}')
+        self._test_scheme("sha256crypt", "{SHA256-CRYPT}")
 
     def test_md5crypt_scheme(self):
-        self._test_scheme('md5crypt', '{MD5-CRYPT}')
+        self._test_scheme("md5crypt", "{MD5-CRYPT}")
 
     def test_sha256_scheme(self):
-        self._test_scheme('sha256', '{SHA256}')
+        self._test_scheme("sha256", "{SHA256}")
 
     def test_md5_scheme(self):
-        self._test_scheme('md5', '{MD5}')
+        self._test_scheme("md5", "{MD5}")
 
     def test_crypt(self):
-        self._test_scheme('crypt', '{CRYPT}')
+        self._test_scheme("crypt", "{CRYPT}")
 
     def test_plain(self):
-        self._test_scheme('plain', '{PLAIN}')
+        self._test_scheme("plain", "{PLAIN}")
diff --git a/modoboa/admin/tests/test_repair.py b/modoboa/admin/tests/test_repair.py
index e3e3b67ef..1a45225b0 100644
--- a/modoboa/admin/tests/test_repair.py
+++ b/modoboa/admin/tests/test_repair.py
@@ -1,22 +1,21 @@
+# -*- coding: utf-8 -*-
+
 """Repair command tests"""
 
 from __future__ import unicode_literals
 
 from django.core import management
 
-from modoboa.lib.permissions import get_object_owner
-from modoboa.lib.permissions import ObjectAccess
+from modoboa.lib.permissions import ObjectAccess, get_object_owner
 from modoboa.lib.tests import ModoTestCase
-
-from .. import factories
-from .. import models
+from .. import factories, models
 
 
 class RepairTestCase(ModoTestCase):
     """TestCase for repair command."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create some data."""
         super(RepairTestCase, cls).setUpTestData()
         factories.populate_database()
@@ -49,7 +48,7 @@ class RepairTestCase(ModoTestCase):
 
     def test_management_command_with_nul_domain(self):
         """Just assume nothing raise when an alias has no domain."""
-        models.Alias.objects.create(address='@modoboa.xxx')
+        models.Alias.objects.create(address="@modoboa.xxx")
         ret = management.call_command("modo", "repair", "--quiet")
         assert ret is None
 
diff --git a/modoboa/admin/tests/test_user.py b/modoboa/admin/tests/test_user.py
index 1c55760ff..3e2238355 100644
--- a/modoboa/admin/tests/test_user.py
+++ b/modoboa/admin/tests/test_user.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """User related tests."""
 
 from __future__ import unicode_literals
@@ -6,7 +8,6 @@ from django.urls import reverse
 
 from modoboa.core.models import User
 from modoboa.lib.tests import ModoTestCase
-
 from ..factories import populate_database
 from ..models import Alias
 
diff --git a/modoboa/admin/tests/utils.py b/modoboa/admin/tests/utils.py
index 8d5d64c26..797fc6dcb 100644
--- a/modoboa/admin/tests/utils.py
+++ b/modoboa/admin/tests/utils.py
@@ -8,12 +8,13 @@ import socket
 
 from dns.name import Name
 from dns.rdtypes.ANY.MX import MX
-from dns.resolver import NoAnswer, NoNameservers, NXDOMAIN, Timeout
+from dns.resolver import NXDOMAIN, NoAnswer, NoNameservers, Timeout
 
 _MX_RECORD_1 = MX("IN", "MX", 10, Name("mx.example.com".split(".")))
 _MX_RECORD_2 = MX("IN", "MX", 10, Name("mx2.example.com".split(".")))
 _BAD_MX_RECORD = MX("IN", "MX", 10, Name("bad-response.example.com".split(".")))
-_DNE_MX_RECORD = MX("IN", "MX", 10, Name("does-not-exist.example.com".split(".")))
+_DNE_MX_RECORD = MX("IN", "MX", 10, Name(
+    "does-not-exist.example.com".split(".")))
 _MX_RECORDS = [_MX_RECORD_1]
 
 _IPV4_RECORD_1 = (socket.AF_INET, socket.SOCK_STREAM, 6, "", ("192.0.2.1", 25))
diff --git a/modoboa/admin/urls.py b/modoboa/admin/urls.py
index eff6fc2bb..bb299ae19 100644
--- a/modoboa/admin/urls.py
+++ b/modoboa/admin/urls.py
@@ -1,4 +1,5 @@
-# pylint: disable=invalid-name, protected-access
+# -*- coding: utf-8 -*-
+
 """Admin urls."""
 
 from __future__ import unicode_literals
@@ -6,12 +7,10 @@ from __future__ import unicode_literals
 from django.conf.urls import url
 
 from . import views
-from .views import import_ as import_views
-from .views import alias as alias_views
-from .views import domain as domain_views
-from .views import export as export_views
-from .views import identity as identity_views
-
+from .views import (
+    alias as alias_views, domain as domain_views, export as export_views,
+    identity as identity_views, import_ as import_views
+)
 
 urlpatterns = [
     url(r'^$', domain_views.index, name="index"),
@@ -27,11 +26,13 @@ urlpatterns = [
         name="domain_quota_list"),
     url(r'^domains/flatlist/$', domain_views.domains_list,
         name="domain_flat_list"),
-    url(r'^domains/new/', domain_views.newdomain, name='domain_add'),
+    url(r'^domains/new/', domain_views.newdomain, name="domain_add"),
     url(r'^domains/(?P<dom_id>\d+)/edit/$', domain_views.editdomain,
         name="domain_change"),
     url(r'^domains/(?P<dom_id>\d+)/delete/$', domain_views.deldomain,
         name="domain_delete"),
+    url(r'^domains/page/$', domain_views.get_next_page,
+        name="domain_page"),
 ]
 
 urlpatterns += [
diff --git a/modoboa/admin/urls_api.py b/modoboa/admin/urls_api.py
index 92e41b86c..63bad995f 100644
--- a/modoboa/admin/urls_api.py
+++ b/modoboa/admin/urls_api.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Admin API urls."""
 
 from __future__ import unicode_literals
@@ -6,7 +8,6 @@ from rest_framework import routers
 
 from . import api
 
-
 router = routers.SimpleRouter()
 router.register(r"domains", api.DomainViewSet, base_name="domain")
 router.register(
diff --git a/modoboa/admin/views/__init__.py b/modoboa/admin/views/__init__.py
index 8c499c185..501c59517 100644
--- a/modoboa/admin/views/__init__.py
+++ b/modoboa/admin/views/__init__.py
@@ -1,12 +1,13 @@
+# -*- coding: utf-8 -*-
+
 """Shortcuts."""
 
 from __future__ import unicode_literals
 
 from .alias import AliasDetailView
-from .identity import AccountDetailView
 from .dns import DNSBLDomainDetailView, MXDomainDetailView
 from .domain import DomainDetailView
-
+from .identity import AccountDetailView
 
 __all__ = [
     "AccountDetailView",
diff --git a/modoboa/admin/views/alias.py b/modoboa/admin/views/alias.py
index a7c97f58b..9b3dfb1c6 100644
--- a/modoboa/admin/views/alias.py
+++ b/modoboa/admin/views/alias.py
@@ -1,24 +1,22 @@
+# -*- coding: utf-8 -*-
+
 """Alias related views."""
 
 from __future__ import unicode_literals
 
-from django.urls import reverse
+from reversion import revisions as reversion
+
+from django.contrib.auth import mixins as auth_mixins
+from django.contrib.auth.decorators import login_required, permission_required
 from django.db import IntegrityError
 from django.shortcuts import render
+from django.urls import reverse
 from django.utils.translation import ugettext as _, ungettext
 from django.views import generic
 
-from django.contrib.auth import mixins as auth_mixins
-from django.contrib.auth.decorators import (
-    login_required, permission_required
-)
-
-from reversion import revisions as reversion
-
 from modoboa.core import signals as core_signals
-from modoboa.lib.exceptions import PermDeniedException, Conflict
+from modoboa.lib.exceptions import Conflict, PermDeniedException
 from modoboa.lib.web_utils import render_to_json_response
-
 from ..forms import AliasForm
 from ..models import Alias
 
@@ -37,7 +35,7 @@ def _validate_alias(request, form, successmsg, callback=None):
             callback(request.user, alias)
         return render_to_json_response(successmsg)
 
-    return render_to_json_response({'form_errors': form.errors}, status=400)
+    return render_to_json_response({"form_errors": form.errors}, status=400)
 
 
 def _new_alias(request, title, action, successmsg,
@@ -87,12 +85,12 @@ def editalias(request, alid, tplname="admin/aliasform.html"):
         return _validate_alias(request, form, successmsg)
 
     ctx = {
-        'action': reverse("admin:alias_change", args=[alias.id]),
-        'formid': 'aliasform',
-        'title': alias.address,
-        'action_label': _('Update'),
-        'action_classes': 'submit',
-        'form': AliasForm(request.user, instance=alias)
+        "action": reverse("admin:alias_change", args=[alias.id]),
+        "formid": "aliasform",
+        "title": alias.address,
+        "action_label": _("Update"),
+        "action_classes": "submit",
+        "form": AliasForm(request.user, instance=alias)
     }
     return render(request, tplname, ctx)
 
diff --git a/modoboa/admin/views/dns.py b/modoboa/admin/views/dns.py
index 591f3f3e5..e202bb818 100644
--- a/modoboa/admin/views/dns.py
+++ b/modoboa/admin/views/dns.py
@@ -1,12 +1,12 @@
+# -*- coding: utf-8 -*-
+
 """DNSBL related views."""
 
 from __future__ import unicode_literals
 
-from django.views import generic
-
-from django.utils.translation import ugettext as _
-
 from django.contrib.auth import mixins as auth_mixins
+from django.utils.translation import ugettext as _
+from django.views import generic
 
 from .. import models
 
diff --git a/modoboa/admin/views/domain.py b/modoboa/admin/views/domain.py
index 4618b294a..824901cbd 100644
--- a/modoboa/admin/views/domain.py
+++ b/modoboa/admin/views/domain.py
@@ -1,34 +1,34 @@
+# -*- coding: utf-8 -*-
+
 """Domain related views."""
 
 from __future__ import unicode_literals
 
 from functools import reduce
 
-from django.urls import reverse
-from django.db.models import Sum
-from django.http import HttpResponseRedirect
-from django.shortcuts import render
-from django.template.loader import render_to_string
-from django.utils.translation import ugettext as _, ungettext
-from django.views import generic
-from django.views.decorators.csrf import ensure_csrf_cookie
+from reversion import revisions as reversion
 
 from django.contrib.auth import mixins as auth_mixins
 from django.contrib.auth.decorators import (
     login_required, permission_required, user_passes_test
 )
-
-from reversion import revisions as reversion
+from django.db.models import Sum
+from django.http import HttpResponseRedirect
+from django.shortcuts import render
+from django.template.loader import render_to_string
+from django.urls import reverse
+from django.utils.translation import ugettext as _, ungettext
+from django.views import generic
+from django.views.decorators.csrf import ensure_csrf_cookie
 
 from modoboa.core import signals as core_signals
-from modoboa.lib.web_utils import render_to_json_response
 from modoboa.lib.exceptions import PermDeniedException
-from modoboa.lib.listing import get_sort_order, get_listing_page
-
+from modoboa.lib.listing import get_listing_page, get_sort_order
+from modoboa.lib.web_utils import render_to_json_response
+from .. import signals
 from ..forms import DomainForm, DomainWizard
 from ..lib import get_domains
 from ..models import Domain, Mailbox
-from .. import signals
 
 
 @login_required
@@ -47,20 +47,20 @@ def _domains(request):
     if extra_filters:
         extra_filters = reduce(
             lambda a, b: a + b, [result[1] for result in extra_filters])
-    filters = dict(
-        (flt, request.GET.get(flt, None))
+    filters = {
+        flt: request.GET.get(flt, None)
         for flt in ["domfilter", "searchquery"] + extra_filters
-    )
-    request.session['domains_filters'] = filters
+    }
+    request.session["domains_filters"] = filters
     domainlist = get_domains(request.user, **filters)
-    if sort_order == 'name':
+    if sort_order == "name":
         domainlist = sorted(
             domainlist,
-            key=lambda d: getattr(d, sort_order), reverse=sort_dir == '-'
+            key=lambda d: getattr(d, sort_order), reverse=sort_dir == "-"
         )
     else:
         domainlist = sorted(domainlist, key=lambda d: d.tags[0]["name"],
-                            reverse=sort_dir == '-')
+                            reverse=sort_dir == "-")
     context = {
         "handle_mailboxes": request.localconfig.parameters.get_value(
             "handle_mailboxes", raise_exception=False),
@@ -108,6 +108,19 @@ def domains(request, tplname="admin/domains.html"):
     })
 
 
+@login_required
+@user_passes_test(
+    lambda u: u.has_perm("admin.view_domains") or
+    u.has_perm("admin.view_mailboxes") or
+    u.has_perm("admin.add_domain")
+)
+def get_next_page(request):
+    """Return the next page of the domain or quota list."""
+    if request.GET.get("objtype", "domain") == "domain":
+        return _domains(request)
+    return list_quotas(request)
+
+
 @login_required
 @permission_required("core.add_user")
 def domains_list(request):
@@ -118,8 +131,6 @@ def domains_list(request):
 @login_required
 @permission_required("admin.add_domain")
 def list_quotas(request):
-    from modoboa.lib.db_utils import db_type
-
     sort_order, sort_dir = get_sort_order(request.GET, "name")
     domains = Domain.objects.get_for_admin(request.user)
     domains = domains.exclude(quota=0)
@@ -164,7 +175,7 @@ def editdomain(request, dom_id):
     if not request.user.can_access(domain):
         raise PermDeniedException
 
-    instances = dict(general=domain)
+    instances = {"general": domain}
     results = signals.get_domain_form_instances.send(
         sender="editdomain", user=request.user, domain=domain)
     for result in results:
@@ -217,7 +228,7 @@ class DomainDetailView(
             "enable_mx_checks": parameters.get_value("enable_mx_checks"),
             "enable_dnsbl_checks": parameters.get_value("enable_dnsbl_checks"),
         })
-        for receiver, widgets in result:
+        for _receiver, widgets in result:
             for widget in widgets:
                 context["templates"][widget["column"]].append(
                     widget["template"])
diff --git a/modoboa/admin/views/export.py b/modoboa/admin/views/export.py
index a2d82e79e..281d864d3 100644
--- a/modoboa/admin/views/export.py
+++ b/modoboa/admin/views/export.py
@@ -1,23 +1,28 @@
+# -*- coding: utf-8 -*-
+
 """Export related views."""
 
 from __future__ import unicode_literals
 
-from backports import csv
-
 from rfc6266 import build_header
 
 from django.contrib.auth.decorators import (
     login_required, permission_required, user_passes_test
 )
-from django.urls import reverse
 from django.http import HttpResponse
 from django.shortcuts import render
-from django.utils.translation import ugettext as _
+from django.urls import reverse
 from django.utils import six
+from django.utils.translation import ugettext as _
 
-from ..forms import ExportIdentitiesForm, ExportDomainsForm
+from ..forms import ExportDomainsForm, ExportIdentitiesForm
 from ..lib import get_domains, get_identities
 
+if six.PY2:
+    from backports import csv
+else:
+    import csv
+
 
 def _export(content, filename):
     """Export a csv file's content
@@ -52,7 +57,7 @@ def export_identities(request):
         fp = six.StringIO()
         csvwriter = csv.writer(fp, delimiter=form.cleaned_data["sepchar"])
         identities = get_identities(
-            request.user, **request.session['identities_filters'])
+            request.user, **request.session["identities_filters"])
         for ident in identities:
             ident.to_csv(csvwriter)
         content = fp.getvalue()
@@ -80,7 +85,7 @@ def export_domains(request):
         fp = six.StringIO()
         csvwriter = csv.writer(fp, delimiter=form.cleaned_data["sepchar"])
         for dom in get_domains(request.user,
-                               **request.session['domains_filters']):
+                               **request.session["domains_filters"]):
             dom.to_csv(csvwriter)
         content = fp.getvalue()
         fp.close()
diff --git a/modoboa/admin/views/identity.py b/modoboa/admin/views/identity.py
index 669a49b62..ac352bc64 100644
--- a/modoboa/admin/views/identity.py
+++ b/modoboa/admin/views/identity.py
@@ -1,33 +1,29 @@
+# -*- coding: utf-8 -*-
+
 """Identity related views."""
 
 from __future__ import unicode_literals
 
+from reversion import revisions as reversion
+
+from django.contrib.auth import mixins as auth_mixins
+from django.contrib.auth.decorators import (
+    login_required, permission_required, user_passes_test
+)
 from django.shortcuts import render
 from django.template.loader import render_to_string
 from django.utils.translation import ugettext as _, ungettext
 from django.views import generic
 from django.views.decorators.csrf import ensure_csrf_cookie
 
-from django.contrib.auth import mixins as auth_mixins
-from django.contrib.auth.decorators import (
-    login_required, permission_required, user_passes_test
-)
-
-from reversion import revisions as reversion
-
 from modoboa.core.models import User
-from modoboa.lib.exceptions import (
-    PermDeniedException, BadRequest
-)
-from modoboa.lib.listing import (
-    get_sort_order, get_listing_page
-)
+from modoboa.lib.exceptions import BadRequest, PermDeniedException
+from modoboa.lib.listing import get_listing_page, get_sort_order
 from modoboa.lib.web_utils import render_to_json_response
-
+from .. import signals
 from ..forms import AccountForm, AccountWizard
 from ..lib import get_identities
-from ..models import Mailbox, Domain
-from .. import signals
+from ..models import Domain, Mailbox
 
 
 @login_required
@@ -36,18 +32,20 @@ from .. import signals
     u.has_perm("admin.add_alias")
 )
 def _identities(request):
-    filters = dict((fname, request.GET.get(fname, None))
-                   for fname in ['searchquery', 'idtfilter', 'grpfilter'])
-    request.session['identities_filters'] = filters
+    filters = {
+        fname: request.GET.get(fname, None)
+        for fname in ["searchquery", "idtfilter", "grpfilter"]
+    }
+    request.session["identities_filters"] = filters
     idents_list = get_identities(request.user, **filters)
     sort_order, sort_dir = get_sort_order(request.GET, "identity",
                                           ["identity", "name_or_rcpt", "tags"])
     if sort_order in ["identity", "name_or_rcpt"]:
         objects = sorted(idents_list, key=lambda o: getattr(o, sort_order),
-                         reverse=sort_dir == '-')
+                         reverse=sort_dir == "-")
     else:
         objects = sorted(idents_list, key=lambda o: o.tags[0],
-                         reverse=sort_dir == '-')
+                         reverse=sort_dir == "-")
     context = {
         "handle_mailboxes": request.localconfig.parameters.get_value(
             "handle_mailboxes", raise_exception=False)
@@ -104,7 +102,7 @@ def list_quotas(request):
                     "* 1048576)) * 100"
                 )
             mboxes = mboxes.extra(
-                select={'quota_usage': select},
+                select={"quota_usage": select},
                 where=["admin_quota.username=%s" % where],
                 tables=["admin_quota", "admin_domain"],
                 order_by=["%s%s" % (sort_dir, sort_order)]
@@ -157,7 +155,7 @@ def identities(request, tplname="admin/identities.html"):
 @permission_required("core.add_user")
 def accounts_list(request):
     accs = User.objects.filter(is_superuser=False) \
-        .exclude(groups__name='SimpleUsers')
+        .exclude(groups__name="SimpleUsers")
     res = [a.username for a in accs.all()]
     return render_to_json_response(res)
 
@@ -179,8 +177,9 @@ def editaccount(request, pk):
         raise PermDeniedException
     mb = account.mailbox if hasattr(account, "mailbox") else None
 
-    instances = dict(
-        general=account, profile=account, mail=mb, perms=account)
+    instances = {
+        "general": account, "profile": account, "mail": mb, "perms": account
+    }
     results = signals.get_account_form_instances.send(
         sender="editaccount", user=request.user, account=account)
     for result in results:
@@ -238,7 +237,7 @@ class AccountDetailView(
         result = signals.extra_account_dashboard_widgets.send(
             self.__class__, user=self.request.user, account=self.object)
         context["templates"] = {"left": [], "right": []}
-        for receiver, widgets in result:
+        for _receiver, widgets in result:
             for widget in widgets:
                 context["templates"][widget["column"]].append(
                     widget["template"])
diff --git a/modoboa/admin/views/import_.py b/modoboa/admin/views/import_.py
index e63a4e849..025d9d0e3 100644
--- a/modoboa/admin/views/import_.py
+++ b/modoboa/admin/views/import_.py
@@ -1,26 +1,31 @@
+# -*- coding: utf-8 -*-
+
 """Import related views."""
 
 from __future__ import unicode_literals
 
-from backports import csv
-
 import io
 
+from reversion import revisions as reversion
+
 from django.contrib.auth.decorators import (
     login_required, permission_required, user_passes_test
 )
-from django.urls import reverse
 from django.db import transaction
 from django.shortcuts import render
+from django.urls import reverse
+from django.utils import six
 from django.utils.encoding import smart_text
 from django.utils.translation import ugettext as _
 
-from reversion import revisions as reversion
-
-from modoboa.lib.exceptions import ModoboaException, Conflict
-
-from ..forms import ImportIdentitiesForm, ImportDataForm
+from modoboa.lib.exceptions import Conflict, ModoboaException
 from .. import signals
+from ..forms import ImportDataForm, ImportIdentitiesForm
+
+if six.PY2:
+    from backports import csv
+else:
+    import csv
 
 
 @reversion.create_revision()
@@ -39,8 +44,8 @@ def importdata(request, formclass=ImportDataForm):
     if form.is_valid():
         try:
             infile = io.TextIOWrapper(
-                request.FILES['sourcefile'].file, encoding="utf8")
-            reader = csv.reader(infile, delimiter=form.cleaned_data['sepchar'])
+                request.FILES["sourcefile"].file, encoding="utf8")
+            reader = csv.reader(infile, delimiter=form.cleaned_data["sepchar"])
         except csv.Error as inst:
             error = smart_text(inst)
         else:
@@ -63,7 +68,7 @@ def importdata(request, formclass=ImportDataForm):
                                 continue
                             raise Conflict(
                                 _("Object already exists: %s"
-                                  % form.cleaned_data['sepchar'].join(row[:2]))
+                                  % form.cleaned_data["sepchar"].join(row[:2]))
                             )
                     cpt += 1
                 msg = _("%d objects imported successfully" % cpt)
diff --git a/modoboa/admin/views/user.py b/modoboa/admin/views/user.py
index 424111919..cb9e18d12 100644
--- a/modoboa/admin/views/user.py
+++ b/modoboa/admin/views/user.py
@@ -1,16 +1,16 @@
+# -*- coding: utf-8 -*-
+
 """SimpleUsers views."""
 
 from __future__ import unicode_literals
 
+from reversion import revisions as reversion
+
+from django.contrib.auth.decorators import login_required
 from django.template.loader import render_to_string
 from django.utils.translation import ugettext as _
 
-from django.contrib.auth.decorators import login_required
-
-from reversion import revisions as reversion
-
 from modoboa.lib.web_utils import render_to_json_response
-
 from ..forms import ForwardForm
 from ..lib import needs_mailbox
 from ..models import Alias
@@ -40,7 +40,7 @@ def forward(request, tplname="admin/forward.html"):
             return render_to_json_response(_("Forward updated"))
 
         return render_to_json_response(
-            {'form_errors': form.errors}, status=400
+            {"form_errors": form.errors}, status=400
         )
 
     form = ForwardForm()
diff --git a/modoboa/core/__init__.py b/modoboa/core/__init__.py
index c9be3cc2e..4efbc2ba0 100644
--- a/modoboa/core/__init__.py
+++ b/modoboa/core/__init__.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """App config for core."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/app_settings.py b/modoboa/core/app_settings.py
index 8934c9773..c0af12596 100644
--- a/modoboa/core/app_settings.py
+++ b/modoboa/core/app_settings.py
@@ -1,21 +1,17 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
 from django import forms
 from django.conf import settings
+from django.contrib.auth import password_validation
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from django.contrib.auth import password_validation
-
 from modoboa.lib import fields as lib_fields
-from modoboa.lib.cryptutils import random_key
 from modoboa.lib.form_utils import (
-    YesNoField, SeparatorField, HorizontalRadioSelect
+    HorizontalRadioSelect, SeparatorField, YesNoField
 )
-from modoboa.parameters import forms as param_forms
-from modoboa.parameters import tools as param_tools
-
+from modoboa.parameters import forms as param_forms, tools as param_tools
 from . import constants
 
 
@@ -40,8 +36,8 @@ class GeneralParametersForm(param_forms.AdminParametersForm):
 
     authentication_type = forms.ChoiceField(
         label=ugettext_lazy("Authentication type"),
-        choices=[('local', ugettext_lazy("Local")),
-                 ('ldap', "LDAP")],
+        choices=[("local", ugettext_lazy("Local")),
+                 ("ldap", "LDAP")],
         initial="local",
         help_text=ugettext_lazy("The backend used for authentication"),
         widget=HorizontalRadioSelect()
@@ -115,16 +111,16 @@ class GeneralParametersForm(param_forms.AdminParametersForm):
 
     ldap_auth_method = forms.ChoiceField(
         label=ugettext_lazy("Authentication method"),
-        choices=[('searchbind', ugettext_lazy("Search and bind")),
-                 ('directbind', ugettext_lazy("Direct bind"))],
-        initial='searchbind',
+        choices=[("searchbind", ugettext_lazy("Search and bind")),
+                 ("directbind", ugettext_lazy("Direct bind"))],
+        initial="searchbind",
         help_text=ugettext_lazy("Choose the authentication method to use"),
         widget=forms.Select(attrs={"class": "form-control"})
     )
 
     ldap_bind_dn = forms.CharField(
         label=ugettext_lazy("Bind DN"),
-        initial='',
+        initial="",
         help_text=ugettext_lazy(
             "The distinguished name to use when binding to the LDAP server. "
             "Leave empty for an anonymous bind"
@@ -135,7 +131,7 @@ class GeneralParametersForm(param_forms.AdminParametersForm):
 
     ldap_bind_password = forms.CharField(
         label=ugettext_lazy("Bind password"),
-        initial='',
+        initial="",
         help_text=ugettext_lazy(
             "The password to use when binding to the LDAP server "
             "(with 'Bind DN')"
@@ -344,7 +340,7 @@ class GeneralParametersForm(param_forms.AdminParametersForm):
     def clean_ldap_user_dn_template(self):
         tpl = self.cleaned_data["ldap_user_dn_template"]
         try:
-            test = tpl % {"user": "toto"}
+            tpl % {"user": "toto"}
         except (KeyError, ValueError):
             raise forms.ValidationError(_("Invalid syntax"))
         return tpl
diff --git a/modoboa/core/apps.py b/modoboa/core/apps.py
index a11d1d5c3..3e4fa2859 100644
--- a/modoboa/core/apps.py
+++ b/modoboa/core/apps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Core config for admin."""
 
 from __future__ import unicode_literals
@@ -30,7 +32,7 @@ class CoreConfig(AppConfig):
         load_core_settings()
 
         # Import these to force registration of checks and signals
-        from . import checks  # noqa:F401
+        from . import checks  # NOQA:F401
         from . import handlers
 
         signals.post_migrate.connect(handlers.create_local_config, sender=self)
diff --git a/modoboa/core/checks/__init__.py b/modoboa/core/checks/__init__.py
index 95e25bed1..c043b6cf9 100644
--- a/modoboa/core/checks/__init__.py
+++ b/modoboa/core/checks/__init__.py
@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
 
+from __future__ import unicode_literals
+
 # Import these to force registration of checks
-from . import settings_checks  # noqa:F401
+from . import settings_checks  # NOQA:F401
diff --git a/modoboa/core/checks/settings_checks.py b/modoboa/core/checks/settings_checks.py
index 797b96538..ebd09db14 100644
--- a/modoboa/core/checks/settings_checks.py
+++ b/modoboa/core/checks/settings_checks.py
@@ -6,7 +6,6 @@ from django.conf import settings
 from django.core.checks import Warning, register
 from django.utils.translation import ugettext as _
 
-
 W001 = Warning(
     _("You have USE_TZ set to False, this may result in issues during "
       "transitions between summer/winter time (ie the same local time occuring "
diff --git a/modoboa/core/commands/__init__.py b/modoboa/core/commands/__init__.py
index f21b36fa7..9a07357ce 100644
--- a/modoboa/core/commands/__init__.py
+++ b/modoboa/core/commands/__init__.py
@@ -1,6 +1,6 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
-from __future__ import unicode_literals, print_function
+from __future__ import print_function, unicode_literals
 
 import argparse
 import os
@@ -17,7 +17,7 @@ class Command(object):
     A valid administrative command must inherit from this class.
     """
 
-    help = "No help available."
+    help = "No help available."  # NOQA:A003
 
     def __init__(self, commands, verbose=False):
         self._commands = commands
@@ -90,10 +90,10 @@ def handle_command_line():
         epilog="""Available commands:
 %s
 """ % "\n".join(["\t%s" % c for c in sorted(commands)]))
-    parser.add_argument('--verbose', action='store_true',
-                        help='Activate verbose output')
-    parser.add_argument('command', type=str,
-                        help='A valid command name')
+    parser.add_argument("--verbose", action="store_true",
+                        help="Activate verbose output")
+    parser.add_argument("command", type=str,
+                        help="A valid command name")
     (args, remaining) = parser.parse_known_args()
 
     if args.command not in commands:
diff --git a/modoboa/core/commands/deploy.py b/modoboa/core/commands/deploy.py
index 11f079f2f..3dcfc0ccb 100644
--- a/modoboa/core/commands/deploy.py
+++ b/modoboa/core/commands/deploy.py
@@ -1,8 +1,8 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """A shortcut to deploy a fresh modoboa instance."""
 
-from __future__ import unicode_literals, print_function
+from __future__ import print_function, unicode_literals
 
 import codecs
 import getpass
@@ -10,26 +10,19 @@ import os
 import shutil
 import subprocess
 import sys
-
 from os.path import isfile
 
-try:
-    import pip
-except ImportError:
-    sys.stderr.write("Error: pip is required to install extensions.\n")
-    sys.exit(2)
+import dj_database_url
 
 import django
 from django.core import management
 from django.template import Context, Template
 from django.utils.encoding import smart_str
-import dj_database_url
+from django.utils.six.moves import input
 
 from modoboa.core.commands import Command
 from modoboa.lib.api_client import ModoAPIClient
-
-if sys.version_info < (3, 0, 0):
-    input = raw_input
+from modoboa.lib.sysutils import exec_cmd
 
 DBCONN_TPL = """
     '{{ conn_name }}': {
@@ -51,47 +44,47 @@ class DeployCommand(Command):
 
     """The ``deploy`` command."""
 
-    help = (
+    help = (  # NOQA:A003
         "Create a fresh django project (calling startproject)"
         " and apply Modoboa specific settings."
     )
 
     def __init__(self, *args, **kwargs):
         super(DeployCommand, self).__init__(*args, **kwargs)
-        self._parser.add_argument('name', type=str,
-                                  help='The name of your Modoboa instance')
+        self._parser.add_argument("name", type=str,
+                                  help="The name of your Modoboa instance")
         self._parser.add_argument(
-            '--collectstatic', action='store_true', default=False,
-            help='Run django collectstatic command'
+            "--collectstatic", action="store_true", default=False,
+            help="Run django collectstatic command"
         )
         self._parser.add_argument(
-            '--dburl', type=str, nargs="+", default=None,
-            help='A database-url with a name')
+            "--dburl", type=str, nargs="+", default=None,
+            help="A database-url with a name")
         self._parser.add_argument(
-            '--domain', type=str, default=None,
-            help='The domain under which you want to deploy modoboa')
+            "--domain", type=str, default=None,
+            help="The domain under which you want to deploy modoboa")
         self._parser.add_argument(
-            '--lang', type=str, default="en-us",
+            "--lang", type=str, default="en-us",
             help="Set the default language"
         )
         self._parser.add_argument(
-            '--timezone', type=str, default="UTC",
+            "--timezone", type=str, default="UTC",
             help="Set the local timezone"
         )
         self._parser.add_argument(
-            '--devel', action='store_true', default=False,
-            help='Create a development instance'
+            "--devel", action="store_true", default=False,
+            help="Create a development instance"
         )
         self._parser.add_argument(
-            '--extensions', type=str, nargs='*',
+            "--extensions", type=str, nargs="*",
             help="The list of extension to deploy"
         )
         self._parser.add_argument(
-            '--dont-install-extensions', action='store_true', default=False,
-            help='Do not install extensions using pip'
+            "--dont-install-extensions", action="store_true", default=False,
+            help="Do not install extensions using pip"
         )
         self._parser.add_argument(
-            '--admin-username', default='admin',
+            "--admin-username", default="admin",
             help="Username of the initial super administrator"
         )
 
@@ -101,7 +94,7 @@ class DeployCommand(Command):
         :param name: the command name
         :param cwd: the directory where the command must be executed
         """
-        cmd = [sys.executable, 'manage.py', name]
+        cmd = [sys.executable, "manage.py", name]
         cmd.extend(args)
         if not self._verbose:
             p = subprocess.Popen(
@@ -120,7 +113,7 @@ class DeployCommand(Command):
                 )
             print("%s failed, check your configuration" % cmd, file=sys.stderr)
 
-    def ask_db_info(self, name='default'):
+    def ask_db_info(self, name="default"):
         """Prompt the user for database information
 
         Gather all information required to create a new database
@@ -130,33 +123,33 @@ class DeployCommand(Command):
         """
         print("Configuring database connection: %s" % name)
         info = {
-            'conn_name': name,
-            'ENGINE': input(
-                'Database type (mysql, postgres or sqlite3): ')
+            "conn_name": name,
+            "ENGINE": input(
+                "Database type (mysql, postgres or sqlite3): ")
         }
-        if info['ENGINE'] not in ['mysql', 'postgres', 'sqlite3']:
-            raise RuntimeError('Unsupported database engine')
+        if info["ENGINE"] not in ["mysql", "postgres", "sqlite3"]:
+            raise RuntimeError("Unsupported database engine")
 
-        if info['ENGINE'] == 'sqlite3':
-            info['ENGINE'] = 'django.db.backends.sqlite3'
-            info['NAME'] = '%s.db' % name
+        if info["ENGINE"] == "sqlite3":
+            info["ENGINE"] = "django.db.backends.sqlite3"
+            info["NAME"] = "%s.db" % name
             return info
-        if info['ENGINE'] == 'postgres':
-            info['ENGINE'] = 'django.db.backends.postgresql_psycopg2'
+        if info["ENGINE"] == "postgres":
+            info["ENGINE"] = "django.db.backends.postgresql_psycopg2"
             default_port = 5432
         else:
-            info['ENGINE'] = 'django.db.backends.mysql'
+            info["ENGINE"] = "django.db.backends.mysql"
             default_port = 3306
-        info['HOST'] = input("Database host (default: 'localhost'): ")
-        info['PORT'] = input(
+        info["HOST"] = input("Database host (default: 'localhost'): ")
+        info["PORT"] = input(
             "Database port (default: '%s'): " % default_port)
         # leave port setting empty, if default value is supplied and
         # leave it to django
-        if info['PORT'] == default_port:
-            info['PORT'] = ''
-        info['NAME'] = input('Database name: ')
-        info['USER'] = input('Username: ')
-        info['PASSWORD'] = getpass.getpass('Password: ')
+        if info["PORT"] == default_port:
+            info["PORT"] = ""
+        info["NAME"] = input("Database name: ")
+        info["USER"] = input("Username: ")
+        info["PASSWORD"] = getpass.getpass("Password: ")
         return info
 
     def _get_extension_list(self):
@@ -188,9 +181,9 @@ class DeployCommand(Command):
     def handle(self, parsed_args):
         django.setup()
         management.call_command(
-            'startproject', parsed_args.name, verbosity=False
+            "startproject", parsed_args.name, verbosity=False
         )
-        path = "%(name)s/%(name)s" % {'name': parsed_args.name}
+        path = "%(name)s/%(name)s" % {"name": parsed_args.name}
         sys.path.append(parsed_args.name)
 
         conn_tpl = Template(DBCONN_TPL)
@@ -206,7 +199,7 @@ class DeployCommand(Command):
                     info = self.ask_db_info(conn_name)
                 # If we set this earlier, our fallback method will never
                 # be triggered
-                info['conn_name'] = conn_name
+                info["conn_name"] = conn_name
                 connections[conn_name] = conn_tpl.render(Context(info))
         else:
             connections["default"] = conn_tpl.render(
@@ -216,7 +209,7 @@ class DeployCommand(Command):
             allowed_host = parsed_args.domain
         else:
             allowed_host = input(
-                'What will be the hostname used to access Modoboa? ')
+                "What will be the hostname used to access Modoboa? ")
             if not allowed_host:
                 allowed_host = "localhost"
         extra_settings = []
@@ -227,9 +220,12 @@ class DeployCommand(Command):
             extensions = [(extension, extension.replace("-", "_"))
                           for extension in extensions]
             if not parsed_args.dont_install_extensions:
-                pip_args = (
-                    ["install"] + [extension[0] for extension in extensions])
-                pip.main(pip_args)
+                cmd = (
+                    sys.executable +
+                    " -m pip install " +
+                    " ".join([extension[0] for extension in extensions])
+                )
+                exec_cmd(cmd, capture_output=False)
             extra_settings = self.find_extra_settings(extensions)
             extensions = [extension[1] for extension in extensions]
 
@@ -238,20 +234,20 @@ class DeployCommand(Command):
         )
 
         mod = __import__(
-            parsed_args.name, globals(), locals(), [smart_str('settings')]
+            parsed_args.name, globals(), locals(), [smart_str("settings")]
         )
         tpl = self._render_template(
             "%s/settings.py.tpl" % self._templates_dir, {
-                'db_connections': connections,
-                'secret_key': mod.settings.SECRET_KEY,
-                'name': parsed_args.name,
-                'allowed_host': allowed_host,
-                'lang': parsed_args.lang,
-                'timezone': parsed_args.timezone,
-                'bower_components_dir': bower_components_dir,
-                'devmode': parsed_args.devel,
-                'extensions': extensions,
-                'extra_settings': extra_settings
+                "db_connections": connections,
+                "secret_key": mod.settings.SECRET_KEY,
+                "name": parsed_args.name,
+                "allowed_host": allowed_host,
+                "lang": parsed_args.lang,
+                "timezone": parsed_args.timezone,
+                "bower_components_dir": bower_components_dir,
+                "devmode": parsed_args.devel,
+                "extensions": extensions,
+                "extra_settings": extra_settings
             }
         )
         with codecs.open("%s/settings.py" % path, "w", "utf-8") as fp:
@@ -264,7 +260,7 @@ class DeployCommand(Command):
         if isfile("%s/settings.pyc" % path):
             os.unlink("%s/settings.pyc" % path)
         self._exec_django_command(
-            "migrate", parsed_args.name, '--noinput'
+            "migrate", parsed_args.name, "--noinput"
         )
         self._exec_django_command(
             "load_initial_data", parsed_args.name,
@@ -272,7 +268,7 @@ class DeployCommand(Command):
         )
         if parsed_args.collectstatic:
             self._exec_django_command(
-                "collectstatic", parsed_args.name, '--noinput'
+                "collectstatic", parsed_args.name, "--noinput"
             )
         self._exec_django_command(
             "set_default_site", parsed_args.name, allowed_host
diff --git a/modoboa/core/commands/help.py b/modoboa/core/commands/help.py
index 88c7efc0b..931264615 100644
--- a/modoboa/core/commands/help.py
+++ b/modoboa/core/commands/help.py
@@ -1,6 +1,6 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
-from __future__ import unicode_literals, print_function
+from __future__ import print_function, unicode_literals
 
 import sys
 
@@ -9,12 +9,12 @@ from . import Command
 
 class HelpCommand(Command):
 
-    help = "Display the help message associated to a specific command"
+    help = "Display the help message associated to a specific command"  # NOQA:A003
 
     def __init__(self, *args, **kwargs):
         super(HelpCommand, self).__init__(*args, **kwargs)
-        self._parser.add_argument('name', type=str,
-                                  help='A command name')
+        self._parser.add_argument("name", type=str,
+                                  help="A command name")
 
     def handle(self, parsed_args):
         if parsed_args.name not in self._commands:
diff --git a/modoboa/core/constants.py b/modoboa/core/constants.py
index ae8587aa3..4d9edb8ad 100644
--- a/modoboa/core/constants.py
+++ b/modoboa/core/constants.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Core application constants."""
 
diff --git a/modoboa/core/context_processors.py b/modoboa/core/context_processors.py
index 72d4ba435..501b2cdc5 100644
--- a/modoboa/core/context_processors.py
+++ b/modoboa/core/context_processors.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom context processors."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/dev_settings.py b/modoboa/core/dev_settings.py
index cbc4b1b54..e282ad7fe 100644
--- a/modoboa/core/dev_settings.py
+++ b/modoboa/core/dev_settings.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 # Development settings
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/extensions.py b/modoboa/core/extensions.py
index a6ea04909..c0287745e 100644
--- a/modoboa/core/extensions.py
+++ b/modoboa/core/extensions.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Extension management."""
 
 from __future__ import unicode_literals
@@ -60,7 +62,7 @@ class ExtensionsPool(object):
         :param ext: a class inheriting from ``Extension``
         :param show: list the extension or not
         """
-        self.extensions[ext.name] = dict(cls=ext, show=show)
+        self.extensions[ext.name] = {"cls": ext, "show": show}
 
     def get_extension(self, name):
         """Retrieve the current instance of an extension."""
@@ -79,7 +81,7 @@ class ExtensionsPool(object):
 
     def load_extension(self, name):
         """Load a registered extension."""
-        __import__(name, locals(), globals(), [smart_str('modo_extension')])
+        __import__(name, locals(), globals(), [smart_str("modo_extension")])
         extinstance = self.get_extension(name)
         if extinstance is None:
             return None
diff --git a/modoboa/core/factories.py b/modoboa/core/factories.py
index 9624ab0d5..e0ad3315f 100644
--- a/modoboa/core/factories.py
+++ b/modoboa/core/factories.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Factories for core application."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/forms.py b/modoboa/core/forms.py
index 668eff33f..78e1f3e08 100644
--- a/modoboa/core/forms.py
+++ b/modoboa/core/forms.py
@@ -1,18 +1,16 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Core forms."""
 
 from __future__ import unicode_literals
 
 from django import forms
+from django.contrib.auth import (
+    forms as auth_forms, get_user_model, password_validation
+)
 from django.db.models import Q
 from django.utils.translation import ugettext as _, ugettext_lazy
 
-from django.contrib.auth import forms as auth_forms
-from django.contrib.auth import get_user_model
-
-from django.contrib.auth import password_validation
-
 from modoboa.core.models import User
 from modoboa.parameters import tools as param_tools
 
diff --git a/modoboa/core/handlers.py b/modoboa/core/handlers.py
index ea1084010..c964861a7 100644
--- a/modoboa/core/handlers.py
+++ b/modoboa/core/handlers.py
@@ -1,27 +1,24 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa core signal handlers."""
 
 from __future__ import unicode_literals
 
 import logging
 
+from reversion import revisions as reversion
+from reversion.models import Version
+
+from django.contrib.sites import models as sites_models
 from django.db.models import signals
 from django.dispatch import receiver
 from django.urls import reverse
 from django.utils.encoding import smart_text
 from django.utils.translation import ugettext as _
 
-from django.contrib.sites import models as sites_models
-
-from reversion import revisions as reversion
-from reversion.models import Version
-
-from modoboa.lib import exceptions
-from modoboa.lib import permissions
+from modoboa.lib import exceptions, permissions
 from modoboa.lib.signals import get_request
-
-from . import models
-from . import signals as core_signals
-from . import utils
+from . import models, signals as core_signals, utils
 
 
 @receiver(reversion.post_revision_commit)
diff --git a/modoboa/core/loggers.py b/modoboa/core/loggers.py
index c6dd24a05..9090f5999 100644
--- a/modoboa/core/loggers.py
+++ b/modoboa/core/loggers.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 import logging
diff --git a/modoboa/core/management/__init__.py b/modoboa/core/management/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/core/management/__init__.py
+++ b/modoboa/core/management/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/core/management/commands/__init__.py b/modoboa/core/management/commands/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/core/management/commands/__init__.py
+++ b/modoboa/core/management/commands/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/core/management/commands/clean_inactive_accounts.py b/modoboa/core/management/commands/clean_inactive_accounts.py
index 87f3dfab2..c67d21358 100644
--- a/modoboa/core/management/commands/clean_inactive_accounts.py
+++ b/modoboa/core/management/commands/clean_inactive_accounts.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Inactive accounts cleanup tool."""
 
 from __future__ import print_function, unicode_literals
@@ -9,14 +11,13 @@ from django.core.management.base import BaseCommand
 from django.utils import timezone
 
 from modoboa.parameters import tools as param_tools
-
 from ... import models
 
 
 class Command(BaseCommand):
     """Management command to clean inactive accounts."""
 
-    help = "Inactive accounts cleanup"
+    help = "Inactive accounts cleanup"  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add extra arguments to command line."""
diff --git a/modoboa/core/management/commands/cleanlogs.py b/modoboa/core/management/commands/cleanlogs.py
index 1513819c3..723cdf9c0 100644
--- a/modoboa/core/management/commands/cleanlogs.py
+++ b/modoboa/core/management/commands/cleanlogs.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import print_function, unicode_literals
 
@@ -15,7 +15,7 @@ from modoboa.parameters import tools as param_tools
 class Command(BaseCommand):
     """Command class."""
 
-    help = "Log table cleanup"
+    help = "Log table cleanup"  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add extra arguments to command line."""
@@ -33,9 +33,9 @@ class Command(BaseCommand):
 
     def handle(self, *args, **options):
         if options["debug"]:
-            l = logging.getLogger("django.db.backends")
-            l.setLevel(logging.DEBUG)
-            l.addHandler(logging.StreamHandler())
+            log = logging.getLogger("django.db.backends")
+            log.setLevel(logging.DEBUG)
+            log.addHandler(logging.StreamHandler())
         self.verbose = options["verbose"]
 
         log_maximum_age = param_tools.get_global_parameter("log_maximum_age")
diff --git a/modoboa/core/management/commands/communicate_with_public_api.py b/modoboa/core/management/commands/communicate_with_public_api.py
index 0aec393d1..2fe2359c8 100644
--- a/modoboa/core/management/commands/communicate_with_public_api.py
+++ b/modoboa/core/management/commands/communicate_with_public_api.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Management command to communicate with public API."""
 
 from __future__ import unicode_literals
@@ -7,14 +9,13 @@ from django.core.management.base import BaseCommand, CommandError
 from modoboa.admin import models as admin_models
 from modoboa.core.extensions import exts_pool
 from modoboa.lib import api_client
-
 from ... import models
 
 
 class Command(BaseCommand):
     """Command class."""
 
-    help = "Communicate with Modoboa public API."
+    help = "Communicate with Modoboa public API."  # NOQA:A003
 
     def handle(self, *args, **options):
         """Command entry point."""
diff --git a/modoboa/core/management/commands/generate_postfix_maps.py b/modoboa/core/management/commands/generate_postfix_maps.py
index 2e0f7fc05..dd4036481 100644
--- a/modoboa/core/management/commands/generate_postfix_maps.py
+++ b/modoboa/core/management/commands/generate_postfix_maps.py
@@ -1,4 +1,7 @@
+# -*- coding: utf-8 -*-
+
 """Management command to generate/update postfix map files."""
+
 from __future__ import print_function, unicode_literals
 
 import copy
@@ -6,16 +9,15 @@ import hashlib
 import os
 import sys
 
+import dj_database_url
+
 from django.conf import settings
 from django.core.management.base import BaseCommand
 from django.template import Context, Template
 from django.utils import timezone
 from django.utils.encoding import force_bytes
 
-import dj_database_url
-
-from ... import signals
-from ... import utils
+from ... import signals, utils
 
 MAP_FILE_TEMPLATE = """# This file was generated on {{ date }} by running:
 # {{ commandline }}
@@ -26,7 +28,7 @@ MAP_FILE_TEMPLATE = """# This file was generated on {{ date }} by running:
 class Command(BaseCommand):
     """Command class."""
 
-    help = "Generate/update postfix map files."
+    help = "Generate/update postfix map files."  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add extra arguments."""
diff --git a/modoboa/core/management/commands/load_initial_data.py b/modoboa/core/management/commands/load_initial_data.py
index 956fde635..d43f27bfc 100644
--- a/modoboa/core/management/commands/load_initial_data.py
+++ b/modoboa/core/management/commands/load_initial_data.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """A management command to load Modoboa initial data:
 
 * Create a default super admin if none exists
@@ -12,19 +14,14 @@ from functools import reduce
 from django.contrib.auth.models import Group
 from django.core.management.base import BaseCommand
 
-from modoboa.lib.cryptutils import random_key
 from modoboa.lib.permissions import add_permissions_to_group
-
-from ... import constants
-from ... import extensions
-from ... import models
-from ... import signals
+from ... import constants, extensions, models, signals
 
 
 class Command(BaseCommand):
     """Command definition."""
 
-    help = "Load Modoboa initial data"
+    help = "Load Modoboa initial data"  # NOQA:A003
 
     def add_arguments(self, parser):
         """Add extra arguments to command."""
diff --git a/modoboa/core/management/commands/set_default_site.py b/modoboa/core/management/commands/set_default_site.py
index d80268a10..8080420bc 100644
--- a/modoboa/core/management/commands/set_default_site.py
+++ b/modoboa/core/management/commands/set_default_site.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """
 A simple managemenent command to update the default site.
 
@@ -7,16 +8,15 @@ See `https://docs.djangoproject.com/en/dev/ref/contrib/sites/`_.
 
 from __future__ import unicode_literals
 
-from django.core.management.base import BaseCommand, CommandError
-
 from django.contrib.sites.models import Site
+from django.core.management.base import BaseCommand, CommandError
 
 
 class Command(BaseCommand):
 
     """Management command to set the default site."""
 
-    help = "Set default site (see django.contrib.sites)"
+    help = "Set default site (see django.contrib.sites)"  # NOQA:A003
 
     def add_arguments(self, parser):
         """Define command arguments."""
diff --git a/modoboa/core/middleware.py b/modoboa/core/middleware.py
index df8f6939a..65135942f 100644
--- a/modoboa/core/middleware.py
+++ b/modoboa/core/middleware.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Core middlewares."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/mocks.py b/modoboa/core/mocks.py
index e593bfc3f..53044082b 100644
--- a/modoboa/core/mocks.py
+++ b/modoboa/core/mocks.py
@@ -1,12 +1,14 @@
+# -*- coding: utf-8 -*-
+
 """Mocks used for testing."""
 
 from __future__ import unicode_literals
 
 import httmock
 
-
 # Modoboa API mocks
 
+
 @httmock.urlmatch(
     netloc=r"api\.modoboa\.org$", path=r"^/1/instances/search/", method="post")
 def modo_api_instance_search(url, request):
diff --git a/modoboa/core/models.py b/modoboa/core/models.py
index c3e7c0a74..bf254989a 100644
--- a/modoboa/core/models.py
+++ b/modoboa/core/models.py
@@ -1,35 +1,33 @@
+# -*- coding: utf-8 -*-
+
 """Core models."""
 
 from __future__ import unicode_literals
 
-from email.header import Header
 import re
-
-from django.conf import settings
-from django.db import models
-from django.urls import reverse
-from django.utils.encoding import (
-    python_2_unicode_compatible, smart_bytes, smart_text, force_str
-)
-from django.utils.functional import cached_property
-from django.utils.translation import ugettext as _, ugettext_lazy
-
-from django.contrib.auth.models import Group, AbstractUser
-from django.contrib.contenttypes.fields import GenericForeignKey
-from django.contrib.contenttypes.models import ContentType
+from email.header import Header
 
 import jsonfield
 from reversion import revisions as reversion
 
+from django.conf import settings
+from django.contrib.auth.models import AbstractUser, Group
+from django.contrib.contenttypes.fields import GenericForeignKey
+from django.contrib.contenttypes.models import ContentType
+from django.db import models
+from django.urls import reverse
+from django.utils.encoding import (
+    force_str, python_2_unicode_compatible, smart_bytes, smart_text
+)
+from django.utils.functional import cached_property
+from django.utils.translation import ugettext as _, ugettext_lazy
+
 from modoboa.core.password_hashers import get_password_hasher
 from modoboa.lib.exceptions import (
-    PermDeniedException, InternalError, BadRequest, Conflict
+    BadRequest, Conflict, InternalError, PermDeniedException
 )
 from modoboa.parameters import tools as param_tools
-
-from . import constants
-from . import signals
-
+from . import constants, signals
 
 try:
     from modoboa.lib.ldap_utils import LDAPAuthBackend
@@ -83,7 +81,7 @@ class User(AbstractUser):
     class Meta(object):
         ordering = ["username"]
         index_together = [
-            ['email', 'is_active']
+            ["email", "is_active"]
         ]
 
     password_expr = re.compile(r'\{([\w\-]+)\}(.+)')
@@ -412,7 +410,7 @@ class ObjectAccess(models.Model):
     user = models.ForeignKey(User, on_delete=models.CASCADE)
     content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
     object_id = models.PositiveIntegerField()
-    content_object = GenericForeignKey('content_type', 'object_id')
+    content_object = GenericForeignKey("content_type", "object_id")
     is_owner = models.BooleanField(default=False)
 
     class Meta(object):
diff --git a/modoboa/core/password_hashers/__init__.py b/modoboa/core/password_hashers/__init__.py
index 6269c666c..0eb35c6fa 100644
--- a/modoboa/core/password_hashers/__init__.py
+++ b/modoboa/core/password_hashers/__init__.py
@@ -1,15 +1,17 @@
+# -*- coding: utf-8 -*-
+
 """
 Password hashers for Modoboa.
 """
 
 from __future__ import unicode_literals
 
-from modoboa.core.password_hashers.base import (
-    PLAINHasher, CRYPTHasher, MD5Hasher, SHA256Hasher
-)
-from modoboa.core.password_hashers.advanced import (
+from modoboa.core.password_hashers.advanced import (  # NOQA:F401
     BLFCRYPTHasher, MD5CRYPTHasher, SHA256CRYPTHasher, SHA512CRYPTHasher
 )
+from modoboa.core.password_hashers.base import (  # NOQA:F401
+    CRYPTHasher, MD5Hasher, PLAINHasher, SHA256Hasher
+)
 
 
 def get_password_hasher(scheme):
@@ -22,8 +24,8 @@ def get_password_hasher(scheme):
     :return: The hasher class
     """
     try:
-        scheme = scheme.replace('-', '')
-        hasher = globals()['%sHasher' % scheme.upper()]
+        scheme = scheme.replace("-", "")
+        hasher = globals()["%sHasher" % scheme.upper()]
     except KeyError:
         hasher = PLAINHasher
     return hasher
diff --git a/modoboa/core/password_hashers/advanced.py b/modoboa/core/password_hashers/advanced.py
index 0f526221c..854cfb9ad 100644
--- a/modoboa/core/password_hashers/advanced.py
+++ b/modoboa/core/password_hashers/advanced.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """
 Advanced (ie. stronger) password hashers.
 
@@ -9,7 +11,6 @@ from __future__ import unicode_literals
 from passlib.hash import bcrypt, md5_crypt, sha256_crypt, sha512_crypt
 
 from modoboa.parameters import tools as param_tools
-
 from .base import PasswordHasher
 
 
@@ -22,7 +23,7 @@ class BLFCRYPTHasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{BLF-CRYPT}' if self._target == 'local' else '{CRYPT}'
+        return "{BLF-CRYPT}" if self._target == "local" else "{CRYPT}"
 
     def _b64encode(self, pwhash):
         return pwhash
@@ -50,7 +51,7 @@ class MD5CRYPTHasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{MD5-CRYPT}' if self._target == 'local' else '{CRYPT}'
+        return "{MD5-CRYPT}" if self._target == "local" else "{CRYPT}"
 
     def _b64encode(self, pwhash):
         return pwhash
@@ -72,7 +73,7 @@ class SHA256CRYPTHasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{SHA256-CRYPT}' if self._target == 'local' else '{CRYPT}'
+        return "{SHA256-CRYPT}" if self._target == "local" else "{CRYPT}"
 
     def _b64encode(self, pwhash):
         return pwhash
@@ -96,7 +97,7 @@ class SHA512CRYPTHasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{SHA512-CRYPT}' if self._target == 'local' else '{CRYPT}'
+        return "{SHA512-CRYPT}" if self._target == "local" else "{CRYPT}"
 
     def _b64encode(self, pwhash):
         return pwhash
diff --git a/modoboa/core/password_hashers/base.py b/modoboa/core/password_hashers/base.py
index a449c8088..93b316919 100644
--- a/modoboa/core/password_hashers/base.py
+++ b/modoboa/core/password_hashers/base.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """
 Base password hashers.
 
@@ -9,11 +11,11 @@ from __future__ import unicode_literals
 import base64
 import crypt
 import hashlib
-from random import Random
 import string
+from random import Random
 
 from django.utils.crypto import constant_time_compare
-from django.utils.encoding import force_text, force_bytes
+from django.utils.encoding import force_bytes, force_text
 
 
 class PasswordHasher(object):
@@ -22,7 +24,7 @@ class PasswordHasher(object):
     Base class of all hashers.
     """
 
-    def __init__(self, target='local'):
+    def __init__(self, target="local"):
         self._target = target
 
     def _encrypt(self, clearvalue, salt=None):
@@ -34,7 +36,7 @@ class PasswordHasher(object):
         :param str pwhash: password hash
         :return: base64 encoded hash or original hash
         """
-        if self._target == 'ldap':
+        if self._target == "ldap":
             return base64.b64encode(pwhash)
         return pwhash
 
@@ -52,7 +54,7 @@ class PasswordHasher(object):
         :return: encrypted password
         """
         pwhash = self._b64encode(self._encrypt(force_text(clearvalue)))
-        return '%s%s' % (self.scheme, force_text(pwhash))
+        return "%s%s" % (self.scheme, force_text(pwhash))
 
     def verify(self, clearvalue, hashed_value):
         """Verify a password against a hashed value.
@@ -74,7 +76,7 @@ class PLAINHasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{PLAIN}'
+        return "{PLAIN}"
 
     def _encrypt(self, clearvalue, salt=None):
         return clearvalue
@@ -89,11 +91,17 @@ class CRYPTHasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{CRYPT}'
+        return "{CRYPT}"
 
     def _encrypt(self, clearvalue, salt=None):
         if salt is None:
-            salt = "".join(Random().sample(string.ascii_letters + string.digits, 2))
+            salt = "".join(
+                Random().sample(
+                    string.ascii_letters +
+                    string.digits,
+                    2
+                )
+            )
         return crypt.crypt(clearvalue, salt)
 
 
@@ -106,7 +114,7 @@ class MD5Hasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{MD5}'
+        return "{MD5}"
 
     def _encrypt(self, clearvalue, salt=None):
         obj = hashlib.md5(force_bytes(clearvalue))
@@ -122,7 +130,7 @@ class SHA256Hasher(PasswordHasher):
     """
     @property
     def scheme(self):
-        return '{SHA256}'
+        return "{SHA256}"
 
     def _encrypt(self, clearvalue, salt=None):
         return hashlib.sha256(force_bytes(clearvalue)).digest()
diff --git a/modoboa/core/password_validation.py b/modoboa/core/password_validation.py
index e69dac511..db3693ba1 100644
--- a/modoboa/core/password_validation.py
+++ b/modoboa/core/password_validation.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom password validators."""
 
 from __future__ import unicode_literals
@@ -19,7 +21,7 @@ class ComplexityValidator(object):
         special_characters = "~!@#$%^&*()_+{}\":;,'[]"
         condition = (
             self.digits > 0 and
-            sum([1 for char in password if char.isdigit()]) < self.digits)
+            sum(1 for char in password if char.isdigit()) < self.digits)
         if condition:
             raise ValidationError(
                 ungettext(
@@ -29,7 +31,7 @@ class ComplexityValidator(object):
                 ).format(self.digits))
         condition = (
             self.lower > 0 and
-            sum([1 for char in password if char.islower()]) < self.lower)
+            sum(1 for char in password if char.islower()) < self.lower)
         if condition:
             raise ValidationError(
                 ungettext(
@@ -40,7 +42,7 @@ class ComplexityValidator(object):
                 .format(self.lower))
         condition = (
             self.upper > 0 and
-            sum([1 for char in password if char.isupper()]) < self.upper)
+            sum(1 for char in password if char.isupper()) < self.upper)
         if condition:
             raise ValidationError(
                 ungettext(
@@ -51,7 +53,7 @@ class ComplexityValidator(object):
                 .format(self.upper))
         condition = (
             self.specials > 0 and
-            sum([1 for char in password if char in special_characters]) <
+            sum(1 for char in password if char in special_characters) <
             self.specials)
         if condition:
             raise ValidationError(
diff --git a/modoboa/core/signals.py b/modoboa/core/signals.py
index 56b640ec9..708759fac 100644
--- a/modoboa/core/signals.py
+++ b/modoboa/core/signals.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa core signals."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/templatetags/__init__.py b/modoboa/core/templatetags/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/core/templatetags/__init__.py
+++ b/modoboa/core/templatetags/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/core/templatetags/core_tags.py b/modoboa/core/templatetags/core_tags.py
index 25ef503af..2b2a707dd 100644
--- a/modoboa/core/templatetags/core_tags.py
+++ b/modoboa/core/templatetags/core_tags.py
@@ -1,24 +1,25 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Custom tags for Core application."""
 
 from __future__ import unicode_literals
 
-from functools import reduce
 import os
-import pkg_resources
 import re
+from functools import reduce
+
+import pkg_resources
 
 from django import template
 from django.conf import settings
-from django.urls import reverse
+from django.contrib.sessions.models import Session
 from django.template.loader import render_to_string
+from django.urls import reverse
 from django.utils import timezone
 from django.utils.encoding import smart_text
 from django.utils.safestring import mark_safe
 from django.utils.translation import get_language, ugettext as _
 
-from django.contrib.sessions.models import Session
-
 from .. import signals
 
 register = template.Library()
@@ -72,7 +73,7 @@ def admin_menu(selection, user):
          "img": "",
          "label": _("Parameters")},
     ]
-    return render_to_string('common/menu.html', {
+    return render_to_string("common/menu.html", {
         "entries": entries,
         "css": "nav nav-sidebar",
         "selection": selection,
@@ -163,7 +164,7 @@ def tohtml(message):
 
 @register.simple_tag
 def visirule(field):
-    if not hasattr(field, 'form') or \
+    if not hasattr(field, "form") or \
             not hasattr(field.form, "visirules") or \
             field.html_name not in field.form.visirules:
         return ""
@@ -191,7 +192,7 @@ class ConnectedUsers(template.Node):
         # Build a list of user ids from that query
         for session in sessions:
             data = session.get_decoded()
-            uid = data.get('_auth_user_id', None)
+            uid = data.get("_auth_user_id", None)
             if uid:
                 uid_list.append(uid)
 
@@ -202,7 +203,7 @@ class ConnectedUsers(template.Node):
                 context[self.varname].append(User.objects.get(pk=uid))
             except User.DoesNotExist:
                 pass
-        return ''
+        return ""
 
 
 @register.tag
@@ -211,7 +212,7 @@ def connected_users(parser, token):
         tag, a, varname = token.split_contents()
     except ValueError:
         raise template.TemplateSyntaxError(
-            'connected_users usage: {% connected_users as users %}'
+            "connected_users usage: {% connected_users as users %}"
         )
     return ConnectedUsers(varname)
 
diff --git a/modoboa/core/tests/__init__.py b/modoboa/core/tests/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/core/tests/__init__.py
+++ b/modoboa/core/tests/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/core/tests/stupid_extension_1/__init__.py b/modoboa/core/tests/stupid_extension_1/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/core/tests/stupid_extension_1/__init__.py
+++ b/modoboa/core/tests/stupid_extension_1/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/core/tests/stupid_extension_1/modo_extension.py b/modoboa/core/tests/stupid_extension_1/modo_extension.py
index 4115447d0..5fdf23318 100644
--- a/modoboa/core/tests/stupid_extension_1/modo_extension.py
+++ b/modoboa/core/tests/stupid_extension_1/modo_extension.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """A stupid extension used for tests."""
 
 from __future__ import unicode_literals
@@ -19,4 +21,5 @@ class StupidExtension1(extensions.ModoExtension):
     def load_initial_data(self):
         raise RuntimeError
 
+
 extensions.exts_pool.register_extension(StupidExtension1)
diff --git a/modoboa/core/tests/stupid_extension_2/__init__.py b/modoboa/core/tests/stupid_extension_2/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/core/tests/stupid_extension_2/__init__.py
+++ b/modoboa/core/tests/stupid_extension_2/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/core/tests/stupid_extension_2/modo_extension.py b/modoboa/core/tests/stupid_extension_2/modo_extension.py
index e2adace26..c7a58d1cc 100644
--- a/modoboa/core/tests/stupid_extension_2/modo_extension.py
+++ b/modoboa/core/tests/stupid_extension_2/modo_extension.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """A stupid extension used for tests."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/tests/stupid_extension_2/urls.py b/modoboa/core/tests/stupid_extension_2/urls.py
index 43f39f251..0e3717f91 100644
--- a/modoboa/core/tests/stupid_extension_2/urls.py
+++ b/modoboa/core/tests/stupid_extension_2/urls.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom urls."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/tests/stupid_extension_2/views.py b/modoboa/core/tests/stupid_extension_2/views.py
index 25d1b2268..c0a372402 100644
--- a/modoboa/core/tests/stupid_extension_2/views.py
+++ b/modoboa/core/tests/stupid_extension_2/views.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from django import http
diff --git a/modoboa/core/tests/test_authentication.py b/modoboa/core/tests/test_authentication.py
index 08c7fb4dc..020f3015b 100644
--- a/modoboa/core/tests/test_authentication.py
+++ b/modoboa/core/tests/test_authentication.py
@@ -1,34 +1,36 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Tests for core application."""
 
 from __future__ import unicode_literals
 
 import smtplib
-
 from unittest import skipIf
-from mock import patch
 
 from django.core import mail
-from django.urls import reverse
 from django.test import override_settings
+from django.urls import reverse
 
-from modoboa.lib.tests import ModoTestCase
-from modoboa.lib.tests import NO_SMTP
+from modoboa.lib.tests import NO_SMTP, ModoTestCase
+from .. import factories, models
 
-from .. import factories
-from .. import models
+try:
+    # mock is part of the Python (>= 3.3) standard library
+    from unittest import mock
+except ImportError:
+    # fall back to the mock backport
+    import mock
 
 
 class AuthenticationTestCase(ModoTestCase):
     """Validate authentication scenarios."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AuthenticationTestCase, cls).setUpTestData()
         cls.account = factories.UserFactory(
-            username="user@test.com", groups=('SimpleUsers',)
+            username="user@test.com", groups=("SimpleUsers",)
         )
 
     def test_authentication(self):
@@ -70,15 +72,15 @@ class PasswordResetTestCase(ModoTestCase):
     """Test password reset service."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(PasswordResetTestCase, cls).setUpTestData()
         cls.account_ok = factories.UserFactory(
             username="user@test.com", secondary_email="test@ext.com",
-            groups=('SimpleUsers',)
+            groups=("SimpleUsers",)
         )
         cls.account_ko = factories.UserFactory(
-            username="user2@test.com", groups=('SimpleUsers',)
+            username="user2@test.com", groups=("SimpleUsers",)
         )
 
     def test_reset_password(self):
@@ -104,7 +106,7 @@ class PasswordResetTestCase(ModoTestCase):
         self.assertEqual(len(mail.outbox), 0)
 
 
-@skipIf(NO_SMTP, 'No SMTP server available')
+@skipIf(NO_SMTP, "No SMTP server available")
 @override_settings(AUTHENTICATION_BACKENDS=(
     "modoboa.lib.authbackends.SMTPBackend",
     "django.contrib.auth.backends.ModelBackend"
@@ -126,24 +128,24 @@ class SMTPAuthenticationTestCase(ModoTestCase):
         self.assertTrue(
             models.User.objects.filter(username=username).exists())
 
-    @patch("smtplib.SMTP")
+    @mock.patch("smtplib.SMTP")
     def test_smtp_authentication(self, mock_smtp):
         """Check simple SMTP authentication."""
         self._test_smtp_authentication(mock_smtp)
 
-    @patch("smtplib.SMTP_SSL")
+    @mock.patch("smtplib.SMTP_SSL")
     @override_settings(AUTH_SMTP_SECURED_MODE="ssl")
     def test_smtp_authentication_over_ssl(self, mock_smtp):
         """Check SMTP authentication over SSL."""
         self._test_smtp_authentication(mock_smtp)
 
-    @patch("smtplib.SMTP")
+    @mock.patch("smtplib.SMTP")
     @override_settings(AUTH_SMTP_SECURED_MODE="starttls")
     def test_smtp_authentication_over_starttls(self, mock_smtp):
         """Check SMTP authentication over STARTTLS."""
         self._test_smtp_authentication(mock_smtp)
 
-    @patch("smtplib.SMTP")
+    @mock.patch("smtplib.SMTP")
     def test_smtp_authentication_failure(self, mock_smtp):
         """Check SMTP authentication failure."""
         instance = mock_smtp.return_value
diff --git a/modoboa/core/tests/test_core.py b/modoboa/core/tests/test_core.py
index 73ffa4b11..5d9a5a605 100644
--- a/modoboa/core/tests/test_core.py
+++ b/modoboa/core/tests/test_core.py
@@ -1,22 +1,20 @@
+# -*- coding: utf-8 -*-
+
 """Tests for core application."""
 
 from __future__ import unicode_literals
 
 import httmock
-
 from dateutil.relativedelta import relativedelta
 from six import StringIO
 
 from django.core import management
-from django.urls import reverse
 from django.test import TestCase
+from django.urls import reverse
 from django.utils import timezone
 
 from modoboa.lib.tests import ModoTestCase
-
-from .. import factories
-from .. import mocks
-from .. import models
+from .. import factories, mocks, models
 
 
 class AuthenticationTestCase(ModoTestCase):
@@ -24,11 +22,11 @@ class AuthenticationTestCase(ModoTestCase):
     """Validate authentication scenarios."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(AuthenticationTestCase, cls).setUpTestData()
         cls.account = factories.UserFactory(
-            username="user@test.com", groups=('SimpleUsers',)
+            username="user@test.com", groups=("SimpleUsers",)
         )
 
     def test_authentication(self):
@@ -105,11 +103,11 @@ class ProfileTestCase(ModoTestCase):
     """Profile related tests."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(ProfileTestCase, cls).setUpTestData()
         cls.account = factories.UserFactory(
-            username="user@test.com", groups=('SimpleUsers',)
+            username="user@test.com", groups=("SimpleUsers",)
         )
 
     def test_update_profile(self):
@@ -164,11 +162,11 @@ class APIAccessFormTestCase(ModoTestCase):
     """Check form access."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(APIAccessFormTestCase, cls).setUpTestData()
         cls.account = factories.UserFactory(
-            username="user@test.com", groups=('SimpleUsers',)
+            username="user@test.com", groups=("SimpleUsers",)
         )
 
     def test_form_access(self):
diff --git a/modoboa/core/tests/test_extensions.py b/modoboa/core/tests/test_extensions.py
index 2ceee2307..af420f526 100644
--- a/modoboa/core/tests/test_extensions.py
+++ b/modoboa/core/tests/test_extensions.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Extensions management related test cases."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/tests/test_ldap.py b/modoboa/core/tests/test_ldap.py
index 2de9be271..54c12a31a 100644
--- a/modoboa/core/tests/test_ldap.py
+++ b/modoboa/core/tests/test_ldap.py
@@ -1,22 +1,21 @@
+# -*- coding: utf-8 -*-
+
 """Tests for core application."""
 
 from __future__ import unicode_literals
 
 from unittest import skipIf
 
-from django.urls import reverse
 from django.test import override_settings
+from django.urls import reverse
 from django.utils.functional import cached_property
 
 from modoboa.lib import exceptions
-from modoboa.lib.tests import ModoTestCase
-from modoboa.lib.tests import NO_LDAP
-
-from .. import factories
-from .. import models
+from modoboa.lib.tests import NO_LDAP, ModoTestCase
+from .. import factories, models
 
 
-@skipIf(NO_LDAP, 'No ldap module installed')
+@skipIf(NO_LDAP, "No ldap module installed")
 class LDAPTestCaseMixin(object):
     """Set of methods used to test LDAP features."""
 
@@ -71,8 +70,8 @@ class LDAPTestCaseMixin(object):
 
 
 @override_settings(AUTHENTICATION_BACKENDS=(
-    'modoboa.lib.authbackends.LDAPBackend',
-    'django.contrib.auth.backends.ModelBackend'
+    "modoboa.lib.authbackends.LDAPBackend",
+    "django.contrib.auth.backends.ModelBackend"
 ))
 class LDAPAuthenticationTestCase(LDAPTestCaseMixin, ModoTestCase):
     """Validate LDAP authentication scenarios."""
@@ -133,16 +132,16 @@ class ProfileTestCase(LDAPTestCaseMixin, ModoTestCase):
     """Profile related tests."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(ProfileTestCase, cls).setUpTestData()
         cls.account = factories.UserFactory(
-            username="user@test.com", groups=('SimpleUsers',)
+            username="user@test.com", groups=("SimpleUsers",)
         )
 
     @override_settings(AUTHENTICATION_BACKENDS=(
-        'modoboa.lib.authbackends.LDAPBackend',
-        'django.contrib.auth.backends.ModelBackend'
+        "modoboa.lib.authbackends.LDAPBackend",
+        "django.contrib.auth.backends.ModelBackend"
     ))
     def test_update_password_ldap(self):
         """Update password for an LDAP user."""
diff --git a/modoboa/core/tests/test_views.py b/modoboa/core/tests/test_views.py
index c9d5a004a..221445348 100644
--- a/modoboa/core/tests/test_views.py
+++ b/modoboa/core/tests/test_views.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Core views test cases."""
 
 from __future__ import unicode_literals
@@ -8,12 +10,8 @@ from django import forms
 from django.urls import reverse
 
 from modoboa.lib.tests import ModoTestCase
-from modoboa.parameters import forms as param_forms
-from modoboa.parameters import tools as param_tools
-
-from .. import factories
-from .. import models
-from .. import signals
+from modoboa.parameters import forms as param_forms, tools as param_tools
+from .. import factories, models, signals
 
 SETTINGS_SAMPLE = {
     "core-check_new_versions": "True",
@@ -93,7 +91,7 @@ class DashboardTestCase(ModoTestCase):
     """Dashboard tests."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create some data."""
         super(DashboardTestCase, cls).setUpTestData()
         cls.dadmin = factories.UserFactory(
@@ -108,12 +106,12 @@ class DashboardTestCase(ModoTestCase):
         url = reverse("core:dashboard")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        self.assertIn("Latest news", response.content.decode('utf-8'))
+        self.assertIn("Latest news", response.content.decode("utf-8"))
         self.client.logout()
         self.client.login(username=self.dadmin.username, password="toto")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        self.assertIn("Latest news", response.content.decode('utf-8'))
+        self.assertIn("Latest news", response.content.decode("utf-8"))
         self.client.logout()
         self.client.login(username=self.user.username, password="toto")
         response = self.client.get(url)
diff --git a/modoboa/core/urls.py b/modoboa/core/urls.py
index d3f34ba00..8b0fd2f95 100644
--- a/modoboa/core/urls.py
+++ b/modoboa/core/urls.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Core urls."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/core/utils.py b/modoboa/core/utils.py
index 4ef209dae..8d992880a 100644
--- a/modoboa/core/utils.py
+++ b/modoboa/core/utils.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Utility functions."""
 
 from __future__ import unicode_literals
@@ -8,7 +10,6 @@ from django.utils.translation import ugettext as _
 
 from modoboa.core.extensions import exts_pool
 from modoboa.lib.api_client import ModoAPIClient
-
 from . import models
 
 
@@ -43,9 +44,9 @@ def check_for_updates(request):
                 continue
             extension["last_version"] = api_extension["version"]
             if (
-                parse_version(api_extension["version"])
-                > parse_version(extension["version"])
-               ):
+                parse_version(api_extension["version"]) >
+                parse_version(extension["version"])
+            ):
                 extension["update"] = True
                 extension["changelog_url"] = api_extension["url"]
                 update_avail = True
diff --git a/modoboa/core/views/__init__.py b/modoboa/core/views/__init__.py
index f23a6b20a..479f86c7f 100644
--- a/modoboa/core/views/__init__.py
+++ b/modoboa/core/views/__init__.py
@@ -1,10 +1,13 @@
+# -*- coding: utf-8 -*-
+
 """Core views."""
 
 from __future__ import unicode_literals
 
 from .admin import (
     check_top_notifications, information, logs, logs_page, parameters,
-    viewsettings)
+    viewsettings
+)
 from .auth import dologin, dologout, password_reset
 from .base import RootDispatchView
 from .dashboard import DashboardView
diff --git a/modoboa/core/views/admin.py b/modoboa/core/views/admin.py
index 6771dedb1..d1ec82099 100644
--- a/modoboa/core/views/admin.py
+++ b/modoboa/core/views/admin.py
@@ -1,28 +1,27 @@
+# -*- coding: utf-8 -*-
+
 """Views available to super administrators only."""
 
 from __future__ import unicode_literals
 
 from functools import reduce
 
-from django.contrib.auth.decorators import (
-    login_required, user_passes_test
-)
+from django.contrib.auth.decorators import login_required, user_passes_test
 from django.shortcuts import render
 from django.template.loader import render_to_string
 from django.utils.translation import ugettext as _
 
 from modoboa.core.models import Log
 from modoboa.core.utils import check_for_updates
-from modoboa.lib.listing import get_sort_order, get_listing_page
+from modoboa.lib.listing import get_listing_page, get_sort_order
 from modoboa.lib.web_utils import render_to_json_response
 from modoboa.parameters import tools as param_tools
-
 from .. import signals
 
 
 @login_required
 @user_passes_test(lambda u: u.is_superuser)
-def viewsettings(request, tplname='core/settings_header.html'):
+def viewsettings(request, tplname="core/settings_header.html"):
     return render(request, tplname, {
         "selection": "settings"
     })
@@ -71,7 +70,7 @@ def get_logs_page(request, page_id=None):
     """Return a page of logs."""
     sort_order, sort_dir = get_sort_order(
         request.GET, "date_created",
-        allowed_values=['date_created', 'level', 'logger', 'message']
+        allowed_values=["date_created", "level", "logger", "message"]
     )
     if page_id is None:
         page_id = request.GET.get("page", None)
diff --git a/modoboa/core/views/auth.py b/modoboa/core/views/auth.py
index 577263144..8bcac9731 100644
--- a/modoboa/core/views/auth.py
+++ b/modoboa/core/views/auth.py
@@ -1,24 +1,24 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Core authentication views."""
 
 from __future__ import unicode_literals
 
 import logging
 
-from django.urls import reverse
+from django.contrib.auth import (
+    authenticate, login, logout, views as auth_views
+)
 from django.http import HttpResponse, HttpResponseRedirect
 from django.template.loader import render_to_string
+from django.urls import reverse
 from django.utils import translation
 from django.utils.translation import ugettext as _
 from django.views.decorators.cache import never_cache
 
-from django.contrib.auth import authenticate, login, logout
-from django.contrib.auth import views as auth_views
-
 from modoboa.core import forms
-
-from .base import find_nextlocation
 from .. import signals
+from .base import find_nextlocation
 
 logger = logging.getLogger("modoboa.auth")
 
@@ -29,7 +29,7 @@ def dologin(request):
     if request.method == "POST":
         form = forms.LoginForm(request.POST)
         if form.is_valid():
-            logger = logging.getLogger('modoboa.auth')
+            logger = logging.getLogger("modoboa.auth")
             user = authenticate(username=form.cleaned_data["username"],
                                 password=form.cleaned_data["password"])
             if user and user.is_active:
diff --git a/modoboa/core/views/base.py b/modoboa/core/views/base.py
index 7b6291bac..32ed7651e 100644
--- a/modoboa/core/views/base.py
+++ b/modoboa/core/views/base.py
@@ -1,13 +1,14 @@
+# -*- coding: utf-8 -*-
+
 """Base core views."""
 
 from __future__ import unicode_literals
 
+from django.contrib.auth import mixins as auth_mixins
 from django.urls import reverse
 from django.utils.http import is_safe_url
 from django.views import generic
 
-from django.contrib.auth import mixins as auth_mixins
-
 from ..extensions import exts_pool
 
 
diff --git a/modoboa/core/views/dashboard.py b/modoboa/core/views/dashboard.py
index 9731096d4..669bc424d 100644
--- a/modoboa/core/views/dashboard.py
+++ b/modoboa/core/views/dashboard.py
@@ -1,15 +1,16 @@
+# -*- coding: utf-8 -*-
+
 """Core dashboard views."""
 
 from __future__ import unicode_literals
 
-from dateutil import parser
 import feedparser
 import requests
+from dateutil import parser
 from requests.exceptions import RequestException
 
-from django.views import generic
-
 from django.contrib.auth import mixins as auth_mixins
+from django.views import generic
 
 from .. import signals
 
@@ -73,7 +74,7 @@ class DashboardView(auth_mixins.AccessMixin, generic.TemplateView):
         # Extra widgets
         result = signals.extra_admin_dashboard_widgets.send(
             sender=self.__class__, user=self.request.user)
-        for receiver, widgets in result:
+        for _receiver, widgets in result:
             for widget in widgets:
                 context["widgets"][widget["column"]].append(
                     widget["template"])
diff --git a/modoboa/core/views/user.py b/modoboa/core/views/user.py
index 91acaff35..22dea631b 100644
--- a/modoboa/core/views/user.py
+++ b/modoboa/core/views/user.py
@@ -1,23 +1,23 @@
+# -*- coding: utf-8 -*-
+
 """Simple user views."""
 
 from __future__ import unicode_literals
 
+from django.contrib.auth.decorators import login_required, user_passes_test
 from django.shortcuts import render
 from django.template.loader import render_to_string
 from django.utils import translation
-from django.utils.translation import ugettext as _
 from django.utils.encoding import force_text
-
-from django.contrib.auth.decorators import login_required, user_passes_test
+from django.utils.translation import ugettext as _
 
 from rest_framework.authtoken.models import Token
 
 from modoboa.lib.cryptutils import encrypt
 from modoboa.lib.web_utils import render_to_json_response
 from modoboa.parameters import tools as param_tools
-
-from ..forms import ProfileForm, APIAccessForm
 from .. import signals
+from ..forms import APIAccessForm, ProfileForm
 
 
 @login_required
@@ -27,7 +27,7 @@ def index(request, tplname="core/user_index.html"):
 
 
 @login_required
-def profile(request, tplname='core/user_profile.html'):
+def profile(request, tplname="core/user_profile.html"):
     """Profile detail/update view."""
     update_password = True
     results = signals.allow_password_change.send(
@@ -50,7 +50,7 @@ def profile(request, tplname='core/user_profile.html'):
                 request.user.language)
             return render_to_json_response(_("Profile updated"))
         return render_to_json_response(
-            {'form_errors': form.errors}, status=400)
+            {"form_errors": form.errors}, status=400)
 
     form = ProfileForm(update_password, instance=request.user)
     return render_to_json_response({
diff --git a/modoboa/lib/__init__.py b/modoboa/lib/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/lib/__init__.py
+++ b/modoboa/lib/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/lib/api_client.py b/modoboa/lib/api_client.py
index afdb80584..70cf45d87 100644
--- a/modoboa/lib/api_client.py
+++ b/modoboa/lib/api_client.py
@@ -1,10 +1,12 @@
+# -*- coding: utf-8 -*-
+
 """A client for Modoboa's public API."""
 
 from __future__ import unicode_literals
 
 import os
-import pkg_resources
 
+import pkg_resources
 import requests
 from requests.exceptions import RequestException
 
diff --git a/modoboa/lib/authbackends.py b/modoboa/lib/authbackends.py
index 18171afbb..adf41feb7 100644
--- a/modoboa/lib/authbackends.py
+++ b/modoboa/lib/authbackends.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom authentication backends."""
 
 from __future__ import unicode_literals
@@ -6,7 +8,7 @@ import smtplib
 
 from django.conf import settings
 
-from modoboa.core.models import populate_callback, User
+from modoboa.core.models import User, populate_callback
 from modoboa.lib.email_utils import split_mailbox
 from modoboa.parameters import tools as param_tools
 
@@ -86,7 +88,7 @@ try:
                 if grp.strip() in ldap_user.group_names:
                     group = "DomainAdmins"
                     break
-            if group == 'SimpleUsers':
+            if group == "SimpleUsers":
                 lpart, domain = split_mailbox(username)
                 if domain is None:
                     return None
diff --git a/modoboa/lib/connections.py b/modoboa/lib/connections.py
index 09287c5e8..5a194f674 100644
--- a/modoboa/lib/connections.py
+++ b/modoboa/lib/connections.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from modoboa.lib.cryptutils import decrypt
@@ -11,27 +13,27 @@ class ConnectionsManager(type):
     This class is specialized in connection management.
     """
 
-    def __init__(cls, name, bases, ctx):
-        super(ConnectionsManager, cls).__init__(name, bases, ctx)
-        cls.instances = {}
+    def __init__(self, name, bases, ctx):
+        super(ConnectionsManager, self).__init__(name, bases, ctx)
+        self.instances = {}
 
-    def __call__(cls, **kwargs):
+    def __call__(self, **kwargs):
         key = None
         if "user" in kwargs:
             key = kwargs["user"]
         else:
             return None
-        if key not in cls.instances:
-            cls.instances[key] = None
+        if key not in self.instances:
+            self.instances[key] = None
         if "password" in kwargs:
             kwargs["password"] = decrypt(kwargs["password"])
 
-        if cls.instances[key] is None:
-            cls.instances[key] = \
-                super(ConnectionsManager, cls).__call__(**kwargs)
+        if self.instances[key] is None:
+            self.instances[key] = \
+                super(ConnectionsManager, self).__call__(**kwargs)
         else:
-            cls.instances[key].refresh(key, kwargs["password"])
-        return cls.instances[key]
+            self.instances[key].refresh(key, kwargs["password"])
+        return self.instances[key]
 
 
 class ConnectionError(Exception):
diff --git a/modoboa/lib/cryptutils.py b/modoboa/lib/cryptutils.py
index 5f729bf50..41815a38f 100644
--- a/modoboa/lib/cryptutils.py
+++ b/modoboa/lib/cryptutils.py
@@ -6,16 +6,16 @@ from __future__ import unicode_literals
 
 import base64
 
+from cryptography.fernet import Fernet
+
 from django.conf import settings
 from django.utils.crypto import get_random_string
 from django.utils.encoding import smart_bytes, smart_text
 
-from cryptography.fernet import Fernet
-
 
 def random_key(length=16):
     """Generate a new key used to encrypt user passwords in session storage."""
-    chars = 'abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(-_=+)'
+    chars = "abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(-_=+)"
     return get_random_string(length, chars)
 
 
diff --git a/modoboa/lib/db_utils.py b/modoboa/lib/db_utils.py
index 8f6999aad..3336ed1ac 100644
--- a/modoboa/lib/db_utils.py
+++ b/modoboa/lib/db_utils.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
@@ -25,7 +25,7 @@ def db_type(cname="default"):
     if cname not in settings.DATABASES:
         raise InternalError(
             _("Connection to database %s not configured" % cname))
-    for t in ['postgres', 'mysql', 'sqlite']:
-        if settings.DATABASES[cname]['ENGINE'].find(t) != -1:
+    for t in ["postgres", "mysql", "sqlite"]:
+        if settings.DATABASES[cname]["ENGINE"].find(t) != -1:
             return t
     return None
diff --git a/modoboa/lib/email_utils.py b/modoboa/lib/email_utils.py
index f043c039c..72d11c42e 100644
--- a/modoboa/lib/email_utils.py
+++ b/modoboa/lib/email_utils.py
@@ -3,12 +3,12 @@
 from __future__ import unicode_literals
 
 import email
-from email.header import Header
-from email.mime.text import MIMEText
-from email.utils import make_msgid, formataddr, formatdate, getaddresses
 import re
 import smtplib
 import time
+from email.header import Header
+from email.mime.text import MIMEText
+from email.utils import formataddr, formatdate, getaddresses, make_msgid
 
 import chardet
 import lxml.html
@@ -23,7 +23,6 @@ from django.utils.translation import ugettext as _
 from modoboa.lib import u2u_decode
 from modoboa.lib.exceptions import InternalError
 
-
 # used by Email()
 _RE_REMOVE_EXTRA_WHITESPACE = re.compile(r"\n\s*\n")
 _RE_CID = re.compile(r".*[ ]*cid=\"([^\"]*)\".*", re.I)
@@ -128,7 +127,7 @@ class Email(object):
         # msg parameter to maintain compatibility with
         # modoboa_webmail.lib.imapemail.ImapEmail
         if header in msg:
-            return "".join([smart_text(v, encoding=(e or 'ascii'))
+            return "".join([smart_text(v, encoding=(e or "ascii"))
                             for v, e in email.header.decode_header(msg[header])
                             ])
         return ""
@@ -180,7 +179,8 @@ class Email(object):
             if content_type == "text":
                 self._parse_text(part, level=level)
             else:
-                # I'm  a dumb mail parser and treat all non-text parts as attachments
+                # I'm  a dumb mail parser and treat all non-text parts as
+                # attachments
                 self._parse_inline_image(part, level=level)
 
     def _parse_inline_image(self, msg, level=0):
@@ -188,7 +188,7 @@ class Email(object):
         cid = None
         if "Content-ID" in msg:
             cid = msg["Content-ID"]
-            if cid.startswith('<') and cid.endswith('>'):
+            if cid.startswith("<") and cid.endswith(">"):
                 cid = cid[1:-1]
         else:
             matches = _RE_CID.match(msg["Content-Type"])
@@ -226,13 +226,13 @@ class Email(object):
             html.rewrite_links(lambda x: None)
 
         cleaner = Cleaner(
-                scripts=True,
-                javascript=True,
-                links=True,
-                page_structure=True,
-                embedded=True,
-                frames=True,
-                add_nofollow=True)
+            scripts=True,
+            javascript=True,
+            links=True,
+            page_structure=True,
+            embedded=True,
+            frames=True,
+            add_nofollow=True)
         mail_text = lxml.html.tostring(cleaner.clean_html(html))
         self.contents["html"] = smart_text(mail_text)
 
@@ -290,18 +290,18 @@ def split_local_part(local_part, delimiter=None):
         # never split these special addresses
         pass
     elif (
-        delimiter == "-"
-        and (local_part.startswith("owner-")
-             or local_part.endswith("-request"))
+        delimiter == "-" and
+         (local_part.startswith("owner-") or
+          local_part.endswith("-request"))
     ):
         # don't split owner-* or *-request if - is the delimiter, they are
         # special addresses used by mail lists.
         pass
     elif (
-        delimiter
-        and delimiter in local_part
-        and local_part[0] != delimiter
-        and local_part[-1] != delimiter
+        delimiter and
+        delimiter in local_part and
+        local_part[0] != delimiter and
+        local_part[-1] != delimiter
     ):
         local_part, extension = local_part.split(delimiter, 1)
 
@@ -342,8 +342,8 @@ def decode(value_bytes, encoding, append_to_error=""):
         except (TypeError, UnicodeDecodeError) as exc:
             six.raise_from(
                 InternalError(
-                    _("unable to determine encoding of string")
-                    + append_to_error
+                    _("unable to determine encoding of string") +
+                    append_to_error
                 ),
                 exc
             )
@@ -379,7 +379,7 @@ def set_email_headers(msg, subject, sender, rcpt):
     """
     import pkg_resources
 
-    msg["Subject"] = Header(subject, 'utf8')
+    msg["Subject"] = Header(subject, "utf8")
     msg["From"] = sender
     msg["To"] = prepare_addresses(rcpt)
     msg["Message-ID"] = make_msgid()
@@ -388,7 +388,7 @@ def set_email_headers(msg, subject, sender, rcpt):
     msg["Date"] = formatdate(time.time(), True)
 
 
-def __sendmail(sender, rcpt, msgstring, server='localhost', port=25):
+def _sendmail(sender, rcpt, msgstring, server="localhost", port=25):
     """Message sending
 
     Return a tuple (True, None) on success, (False, error message)
@@ -425,9 +425,9 @@ def sendmail_simple(
     :param content: message's content
     :return: tuple
     """
-    msg = MIMEText(content, _charset='utf-8')
+    msg = MIMEText(content, _charset="utf-8")
     set_email_headers(msg, subject, sender, rcpt)
-    return __sendmail(sender, rcpt, msg.as_string(), **kwargs)
+    return _sendmail(sender, rcpt, msg.as_string(), **kwargs)
 
 
 def sendmail_fromfile(sender, rcpt, fname):
@@ -453,4 +453,4 @@ To: %s
     content += fp.read()
     fp.close()
 
-    return __sendmail(sender, rcpt, content)
+    return _sendmail(sender, rcpt, content)
diff --git a/modoboa/lib/exceptions.py b/modoboa/lib/exceptions.py
index 4bdd15896..9a672e8ca 100644
--- a/modoboa/lib/exceptions.py
+++ b/modoboa/lib/exceptions.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """
 :mod:`exceptions` --- Custom Modoboa exceptions
 -----------------------------------------------
@@ -17,9 +18,9 @@ class ModoboaException(Exception):
     http_code = None
 
     def __init__(self, *args, **kwargs):
-        if 'http_code' in kwargs:
-            self.http_code = kwargs['http_code']
-            del kwargs['http_code']
+        if "http_code" in kwargs:
+            self.http_code = kwargs["http_code"]
+            del kwargs["http_code"]
         super(ModoboaException, self).__init__(*args, **kwargs)
 
 
diff --git a/modoboa/lib/fields.py b/modoboa/lib/fields.py
index 4dcaf2998..52f53cd72 100644
--- a/modoboa/lib/fields.py
+++ b/modoboa/lib/fields.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom form fields."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/lib/form_utils.py b/modoboa/lib/form_utils.py
index 74abb7a37..937e0e8d9 100644
--- a/modoboa/lib/form_utils.py
+++ b/modoboa/lib/form_utils.py
@@ -1,12 +1,12 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Form management utilities."""
 
 from __future__ import unicode_literals
 
 import abc
-from collections import OrderedDict
 import re
+from collections import OrderedDict
 
 from django.forms import TypedChoiceField
 from django.forms.fields import Field
@@ -18,8 +18,7 @@ from django.utils.translation import ugettext as _, ugettext_lazy
 from modoboa.lib.exceptions import BadRequest
 from modoboa.lib.web_utils import render_to_json_response
 
-
-ABC = abc.ABCMeta(force_str('ABC'), (object,), {})
+ABC = abc.ABCMeta(force_str("ABC"), (object,), {})
 
 
 class WizardStep(object):
@@ -87,7 +86,7 @@ class WizardForm(ABC):
         result = {}
         for step in self.steps:
             for name, value in list(step.form.errors.items()):
-                if name == '__all__':
+                if name == "__all__":
                     continue
                 result[name] = value
         return result
@@ -283,8 +282,8 @@ class TabForms(object):
         """
         result = {}
         for f in self.forms:
-            for name, value in list(f['instance'].errors.items()):
-                if name == '__all__':
+            for name, value in list(f["instance"].errors.items()):
+                if name == "__all__":
                     continue
                 result[name] = value
         return result
@@ -298,9 +297,9 @@ class TabForms(object):
         to_remove = []
         for f in self.forms:
             if mandatory_only and \
-               ('mandatory' not in f or not f["mandatory"]):
+               ("mandatory" not in f or not f["mandatory"]):
                 continue
-            elif optional_only and ('mandatory' in f and f["mandatory"]):
+            elif optional_only and ("mandatory" in f and f["mandatory"]):
                 continue
             if not self._before_is_valid(f):
                 to_remove.append(f)
@@ -349,7 +348,7 @@ class TabForms(object):
                 self.save()
                 return self.done()
             return render_to_json_response(
-                {'form_errors': self.errors}, status=400
+                {"form_errors": self.errors}, status=400
             )
         context = {
             "tabs": self,
diff --git a/modoboa/lib/imap_utf7.py b/modoboa/lib/imap_utf7.py
index f1a2af3bd..34efc3778 100644
--- a/modoboa/lib/imap_utf7.py
+++ b/modoboa/lib/imap_utf7.py
@@ -61,13 +61,13 @@ PRINTABLE = set(range(0x20, 0x26)) | set(range(0x27, 0x7f))
 
 
 def modified_utf7(s):
-    s_utf7 = s.encode('utf-7')
-    return s_utf7[1:-1].replace(b'/', b',')
+    s_utf7 = s.encode("utf-7")
+    return s_utf7[1:-1].replace(b"/", b",")
 
 
-def doB64(_in, r):
+def doB64(_in, r):  # NOQA:N802
     if _in:
-        r.extend([b'&', modified_utf7(''.join(_in)), b'-'])
+        r.extend([b"&", modified_utf7("".join(_in)), b"-"])
         del _in[:]
 
 
@@ -78,32 +78,32 @@ def encoder(s):
         if ord(c) in PRINTABLE:
             doB64(_in, r)
             r.append(c.encode())
-        elif c == '&':
+        elif c == "&":
             doB64(_in, r)
-            r.append(b'&-')
+            r.append(b"&-")
         else:
             _in.append(c)
     doB64(_in, r)
-    return (b''.join(r), len(s))
+    return (b"".join(r), len(s))
 
 
 # decoding
 
 
 def modified_unutf7(s):
-    s_utf7 = b'+' + s.replace(b',', b'/') + b'-'
-    return s_utf7.decode('utf-7')
+    s_utf7 = b"+" + s.replace(b",", b"/") + b"-"
+    return s_utf7.decode("utf-7")
 
 
 def decoder(s):
     r = []
     decoded = bytearray()
     for c in s:
-        if c == ord('&') and not decoded:
-            decoded.append(ord('&'))
-        elif c == ord('-') and decoded:
+        if c == ord("&") and not decoded:
+            decoded.append(ord("&"))
+        elif c == ord("-") and decoded:
             if len(decoded) == 1:
-                r.append('&')
+                r.append("&")
             else:
                 r.append(modified_unutf7(decoded[1:]))
             decoded = bytearray()
@@ -113,22 +113,22 @@ def decoder(s):
             r.append(chr(c))
     if decoded:
         r.append(modified_unutf7(decoded[1:]))
-    bin_str = ''.join(r)
+    bin_str = "".join(r)
     return (bin_str, len(s))
 
 
 class StreamReader(codecs.StreamReader):
-    def decode(self, s, errors='strict'):
+    def decode(self, s, errors="strict"):
         return decoder(s)
 
 
 class StreamWriter(codecs.StreamWriter):
-    def decode(self, s, errors='strict'):
+    def decode(self, s, errors="strict"):
         return encoder(s)
 
 
 def imap4_utf_7(name):
-    if name == 'imap4-utf-7':
+    if name == "imap4-utf-7":
         return (encoder, decoder, StreamReader, StreamWriter)
 
 
@@ -137,69 +137,69 @@ codecs.register(imap4_utf_7)
 
 # testing methods
 
-def imapUTF7Encode(ust):
+def imapUTF7Encode(ust):  # NOQA:N802
     "Returns imap utf-7 encoded version of string"
-    return ust.encode('imap4-utf-7')
+    return ust.encode("imap4-utf-7")
 
 
-def imapUTF7EncodeSequence(seq):
+def imapUTF7EncodeSequence(seq):  # NOQA:N802
     "Returns imap utf-7 encoded version of strings in sequence"
     return [imapUTF7Encode(itm) for itm in seq]
 
 
-def imapUTF7Decode(st):
+def imapUTF7Decode(st):  # NOQA:N802
     "Returns utf7 encoded version of imap utf-7 string"
-    return st.decode('imap4-utf-7')
+    return st.decode("imap4-utf-7")
 
 
-def imapUTF7DecodeSequence(seq):
+def imapUTF7DecodeSequence(seq):  # NOQA:N802
     "Returns utf7 encoded version of imap utf-7 strings in sequence"
     return [imapUTF7Decode(itm) for itm in seq]
 
 
-def utf8Decode(st):
+def utf8Decode(st):  # NOQA:N802
     "Returns utf7 encoded version of imap utf-7 string"
-    return st.decode('utf-8')
+    return st.decode("utf-8")
 
 
-def utf7SequenceToUTF8(seq):
+def utf7SequenceToUTF8(seq):  # NOQA:N802
     "Returns utf7 encoded version of imap utf-7 strings in sequence"
-    return [itm.decode('imap4-utf-7').encode('utf-8') for itm in seq]
+    return [itm.decode("imap4-utf-7").encode("utf-8") for itm in seq]
 
 
-__all__ = ['imapUTF7Encode', 'imapUTF7Decode', ]
+__all__ = ["imapUTF7Encode", "imapUTF7Decode", ]
 
-if __name__ == '__main__':
+if __name__ == "__main__":
 
-    # print u'břx'.encode('imap4-utf-7')
+    # print 'bøx'.encode('imap4-utf-7')
     # print 'expected b&APg-x'
 
-    # print u'bĺx'.encode('imap4-utf-7')
+    # print 'bĂĄx'.encode('imap4-utf-7')
     # print 'expected b&AOU-x'
 
-    print('#######')
-    print('břx')
-    e = imapUTF7Encode(u'břx')
+    print("#######")
+    print("bøx")
+    e = imapUTF7Encode("bøx")
     print(e)
-    print(imapUTF7Decode(e).encode('latin-1'))
+    print(imapUTF7Decode(e).encode("latin-1"))
 
-    print('#######')
-    print('bĺx')
-    e = imapUTF7Encode(u'bĺx')
+    print("#######")
+    print("bĂĄx")
+    e = imapUTF7Encode("bĂĄx")
     print(e)
-    print(imapUTF7Decode(e).encode('latin-1'))
+    print(imapUTF7Decode(e).encode("latin-1"))
 
-    print('#######')
-    print('~/bĺgř')
-    e = imapUTF7Encode(u'~/bĺgř')
+    print("#######")
+    print("~/bågø")
+    e = imapUTF7Encode("~/bågø")
     print(e)
-    print(imapUTF7Decode(e).encode('latin-1'))
+    print(imapUTF7Decode(e).encode("latin-1"))
 
-    print('#######')
-    print('Ting & Sĺger')
-    e = imapUTF7Encode(u'Ting & Sĺger')
+    print("#######")
+    print("Ting & SĂĄger")
+    e = imapUTF7Encode("Ting & SĂĄger")
     print(e)
-    print(imapUTF7Decode(e).encode('latin-1'))
+    print(imapUTF7Decode(e).encode("latin-1"))
 
     # e = imapUTF7Decode('b&AOU-x')
     # print e.encode('latin-1')
@@ -207,13 +207,13 @@ if __name__ == '__main__':
     # e = imapUTF7Decode('b&APg-x')
     # print e.encode('latin-1')
 
-    print('#######')
-    print('~/Fřlder/mailbĺx & stuff + more')
-    n = u'~/Fřlder/mailbĺx & stuff + more'
+    print("#######")
+    print("~/Følder/mailbåx & stuff + more")
+    n = "~/Følder/mailbåx & stuff + more"
     e = imapUTF7Encode(n)
     print(e)
-    print(imapUTF7Decode(e).encode('latin-1'))
+    print(imapUTF7Decode(e).encode("latin-1"))
 
-    print('#######')
-    print('~peter/mail/&ZeVnLIqe-/&U,BTFw-')
-    print(imapUTF7Decode('~peter/mail/&ZeVnLIqe-/&U,BTFw-').encode('utf-8'))
+    print("#######")
+    print("~peter/mail/&ZeVnLIqe-/&U,BTFw-")
+    print(imapUTF7Decode("~peter/mail/&ZeVnLIqe-/&U,BTFw-").encode("utf-8"))
diff --git a/modoboa/lib/ldap_utils.py b/modoboa/lib/ldap_utils.py
index 57767b69f..c7ec9235d 100644
--- a/modoboa/lib/ldap_utils.py
+++ b/modoboa/lib/ldap_utils.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """
 A collection of LDAP based classes/functions.
@@ -38,9 +38,9 @@ from __future__ import unicode_literals
 import ldap
 
 from django.conf import settings
-from django.utils.translation import ugettext as _
-from django.utils.encoding import force_bytes
 from django.utils import six
+from django.utils.encoding import force_bytes, force_str
+from django.utils.translation import ugettext as _
 
 from modoboa.core.password_hashers import get_password_hasher
 from modoboa.lib.exceptions import InternalError
@@ -70,13 +70,12 @@ class LDAPAuthBackend(object):
 
     def _get_conn(self, dn, password):
         """Get a connection from the server."""
-        kwargs = {}
-        if six.PY3:
-            kwargs['bytes_mode'] = False
-        conn = ldap.initialize(self.server_uri, **kwargs)
+        conn = ldap.initialize(self.server_uri, bytes_mode=six.PY2)
         conn.set_option(ldap.OPT_X_TLS_DEMAND, True)
         conn.set_option(ldap.OPT_DEBUG_LEVEL, 255)
-        conn.simple_bind_s(dn, password)
+        conn.simple_bind_s(
+            force_str(dn), force_str(password)
+        )
         return conn
 
     def connect_to_server(self, user, password):
@@ -98,7 +97,9 @@ class LDAPAuthBackend(object):
         sbase = self.global_params["ldap_search_base"]
         sfilter = self.global_params["ldap_search_filter"]
         sfilter = sfilter % {"user": user}
-        res = self.conn.search_s(sbase, ldap.SCOPE_SUBTREE, sfilter)
+        res = self.conn.search_s(
+            force_str(sbase), ldap.SCOPE_SUBTREE, force_str(sfilter)
+        )
         try:
             dn = res[0][0]
         except IndexError:
@@ -121,13 +122,13 @@ class LDAPAuthBackend(object):
         user_dn = self._find_user_dn(user)
         if self.ldap_ad:
             newpassword = (
-                ('"%s"' % newpassword).encode('utf-16').lstrip('\377\376')
+                ('"%s"' % newpassword).encode("utf-16").lstrip("\377\376")
             )
         ldif = [(ldap.MOD_REPLACE,
-                 self.pwd_attr,
+                 force_str(self.pwd_attr),
                  force_bytes(self._crypt_password(newpassword)))]
         try:
-            self.conn.modify_s(user_dn, ldif)
+            self.conn.modify_s(force_str(user_dn), ldif)
         except ldap.LDAPError as e:
             raise InternalError(
                 _("Failed to update password: {}").format(e))
diff --git a/modoboa/lib/listing.py b/modoboa/lib/listing.py
index c77e7dcf1..8237719fe 100644
--- a/modoboa/lib/listing.py
+++ b/modoboa/lib/listing.py
@@ -1,6 +1,8 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
-from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
+from django.core.paginator import EmptyPage, PageNotAnInteger, Paginator
 
 from modoboa.parameters import tools as param_tools
 
diff --git a/modoboa/lib/middleware.py b/modoboa/lib/middleware.py
index 684726d65..2273e6b1e 100644
--- a/modoboa/lib/middleware.py
+++ b/modoboa/lib/middleware.py
@@ -1,15 +1,15 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Custom middlewares."""
 
 from __future__ import unicode_literals
 
 from django.http import HttpResponseRedirect
-from django.utils.encoding import smart_text
 from django.utils.deprecation import MiddlewareMixin
+from django.utils.encoding import smart_text
 
-from modoboa.lib.exceptions import ModoboaException
 from modoboa.lib import signals as lib_signals
+from modoboa.lib.exceptions import ModoboaException
 from modoboa.lib.web_utils import (
     _render_error, ajax_response, render_to_json_response
 )
@@ -19,7 +19,7 @@ class AjaxLoginRedirect(MiddlewareMixin):
 
     def process_response(self, request, response):
         if request.is_ajax():
-            if type(response) == HttpResponseRedirect:
+            if isinstance(response, HttpResponseRedirect):
                 response.status_code = 278
         return response
 
@@ -41,7 +41,7 @@ class CommonExceptionCatcher(MiddlewareMixin):
                 smart_text(exception), status=exception.http_code
             )
         return _render_error(
-            request, user_context=dict(error=smart_text(exception))
+            request, user_context={"error": smart_text(exception)}
         )
 
 
diff --git a/modoboa/lib/paginator.py b/modoboa/lib/paginator.py
index 2c5658a54..9006ded56 100644
--- a/modoboa/lib/paginator.py
+++ b/modoboa/lib/paginator.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """
 Custom pagination tools.
 """
diff --git a/modoboa/lib/permissions.py b/modoboa/lib/permissions.py
index 73cc4439c..b1705bd77 100644
--- a/modoboa/lib/permissions.py
+++ b/modoboa/lib/permissions.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Object level permissions."""
 
 from __future__ import unicode_literals
@@ -6,8 +7,7 @@ from __future__ import unicode_literals
 from django.contrib.auth.models import Group, Permission
 from django.contrib.contenttypes.models import ContentType
 
-from modoboa.core import constants as core_constants
-from modoboa.core import signals as core_signals
+from modoboa.core import constants as core_constants, signals as core_signals
 from modoboa.core.models import ObjectAccess, User
 
 
diff --git a/modoboa/lib/signals.py b/modoboa/lib/signals.py
index f203de7c3..46c4795b1 100644
--- a/modoboa/lib/signals.py
+++ b/modoboa/lib/signals.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom signals."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/lib/singleton.py b/modoboa/lib/singleton.py
index da4210794..2033d7c6e 100644
--- a/modoboa/lib/singleton.py
+++ b/modoboa/lib/singleton.py
@@ -1,15 +1,18 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
+
 # works in Python 2 & 3
 class _Singleton(type):
     _instances = {}
 
-    def __call__(cls, *args, **kwargs):
-        if cls not in cls._instances:
-            cls._instances[cls] = \
-                super(_Singleton, cls).__call__(*args, **kwargs)
-        return cls._instances[cls]
+    def __call__(self, *args, **kwargs):
+        if self not in self._instances:
+            self._instances[self] = \
+                super(_Singleton, self).__call__(*args, **kwargs)
+        return self._instances[self]
 
 
-class Singleton(_Singleton('SingletonMeta', (object,), {})):
+class Singleton(_Singleton("SingletonMeta", (object,), {})):
     pass
diff --git a/modoboa/lib/sysutils.py b/modoboa/lib/sysutils.py
index aff56e97a..3d21445bf 100644
--- a/modoboa/lib/sysutils.py
+++ b/modoboa/lib/sysutils.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """
 This module extra functions/shortcuts to communicate with the system
@@ -7,9 +7,9 @@ This module extra functions/shortcuts to communicate with the system
 
 from __future__ import unicode_literals
 
-import subprocess
 import inspect
 import re
+import subprocess
 
 
 def exec_cmd(cmd, sudo_user=None, pinput=None, capture_output=True, **kwargs):
diff --git a/modoboa/lib/templatetags/__init__.py b/modoboa/lib/templatetags/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/lib/templatetags/__init__.py
+++ b/modoboa/lib/templatetags/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/lib/templatetags/form_tags.py b/modoboa/lib/templatetags/form_tags.py
index 11db3bf90..796fce0be 100644
--- a/modoboa/lib/templatetags/form_tags.py
+++ b/modoboa/lib/templatetags/form_tags.py
@@ -1,14 +1,15 @@
+# -*- coding: utf-8 -*-
+
 """
 Form rendering tags.
 """
 
 from __future__ import unicode_literals
 
-from django import forms
-from django import template
+from django import forms, template
+from django.template.loader import render_to_string
 from django.utils.encoding import smart_text
 from django.utils.safestring import mark_safe
-from django.template.loader import render_to_string
 
 from modoboa.lib.form_utils import SeparatorField
 
@@ -19,7 +20,7 @@ register = template.Library()
 def render_form(form, tpl=None):
     """Render a form."""
     if tpl is not None:
-        return render_to_string(tpl, dict(form=form))
+        return render_to_string(tpl, {"form": form})
 
     ret = ""
     for field in form:
@@ -45,7 +46,7 @@ def render_field(
     """Render a field."""
     from modoboa.core.templatetags.core_tags import visirule
 
-    if type(field.field) is SeparatorField:
+    if isinstance(field.field, SeparatorField):
         return "<h5%s>%s</h5>" % (visirule(field), smart_text(field.label))
     configure_field_classes(field)
     context = {
@@ -76,10 +77,11 @@ def render_fields_group(form, pattern):
         group += [bfield]
         cpt += 1
 
-    return render_to_string("common/generic_fields_group.html", dict(
-        label=label, help_text=first.help_text, group=group, haserror=haserror,
-        pattern=pattern
-    ))
+    return render_to_string(
+        "common/generic_fields_group.html",
+        {"label": label, "help_text": first.help_text, "group": group,
+         "haserror": haserror, "pattern": pattern}
+    )
 
 
 @register.simple_tag
diff --git a/modoboa/lib/templatetags/lib_tags.py b/modoboa/lib/templatetags/lib_tags.py
index ef7a9da2d..41a086d31 100644
--- a/modoboa/lib/templatetags/lib_tags.py
+++ b/modoboa/lib/templatetags/lib_tags.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Custom template tags."""
 
 from __future__ import unicode_literals
@@ -6,7 +7,7 @@ from __future__ import unicode_literals
 from datetime import datetime
 
 from django import template
-from django.template import Template, Context
+from django.template import Context, Template
 from django.utils.safestring import mark_safe
 from django.utils.translation import ugettext as _
 
@@ -16,7 +17,7 @@ register = template.Library()
 
 
 @register.simple_tag
-def join(items, sep=','):
+def join(items, sep=","):
     res = ""
     for k, v in list(items.items()):
         if res != "":
@@ -35,8 +36,8 @@ def alert(msg, typ):
     t = Template("""<div class="alert alert-{{ type }}" role="alert">
 <button type="button" class="close" data-dismiss="alert"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
 {{ msg }}
-</div>""")
-    return t.render(Context(dict(type=typ, msg=msg)))
+</div>""")  # NOQA:E501
+    return t.render(Context({"type": typ, "msg": msg}))
 
 
 @register.simple_tag
@@ -50,8 +51,8 @@ class="{{ mdclass }}{% if link.class %} {{ link.class }}{% endif %}"
 {% for attr, value in link.extra_attributes.items %} {{ attr }}="{{ value }}"{% endfor %}
 >
 {% if link.img %}<i class="{{ link.img }}"></i>{% endif %}
-{{ link.label }}</a>""")
-    return t.render(Context(dict(link=linkdef, mdclass=mdclass)))
+{{ link.label }}</a>""")  # NOQA:E501
+    return t.render(Context({"link": linkdef, "mdclass": mdclass}))
 
 
 @register.simple_tag
@@ -76,7 +77,7 @@ def render_tags(tags):
   <a href="#" class="filter {{ tag.type }}" name="{{ tag.name }}">{{ tag.label }}</a>
 </span>
 {% endfor %}
-""")
+""")  # NOQA:E501
     return t.render(Context({"tags": tags}))
 
 
@@ -100,7 +101,7 @@ def extra_static_content(caller, st_type, user):
     )
 
 
-@register.filter(name='localize_header_name')
+@register.filter(name="localize_header_name")
 def localize_header_name(headername):
     """ Localizes the header names """
     names = {
diff --git a/modoboa/lib/test_utils.py b/modoboa/lib/test_utils.py
index 640c199f0..51b4be356 100644
--- a/modoboa/lib/test_utils.py
+++ b/modoboa/lib/test_utils.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Tools for top level testing (ie. when ran by Travis)."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/lib/tests/__init__.py b/modoboa/lib/tests/__init__.py
index ace3d977e..7eb668515 100644
--- a/modoboa/lib/tests/__init__.py
+++ b/modoboa/lib/tests/__init__.py
@@ -13,11 +13,10 @@ from rest_framework.authtoken.models import Token
 from rest_framework.test import APITestCase
 
 from modoboa.core import models as core_models
-
 from .. import sysutils
 
 try:
-    s = socket.create_connection(('127.0.0.1', 25))
+    s = socket.create_connection(("127.0.0.1", 25))
     s.close()
     NO_SMTP = False
 except socket.error:
@@ -72,21 +71,21 @@ class ModoTestCase(ParametersMixin, TestCase):
         if params is None:
             params = {}
         response = getattr(self.client, method)(
-            url, params, HTTP_X_REQUESTED_WITH='XMLHttpRequest')
+            url, params, HTTP_X_REQUESTED_WITH="XMLHttpRequest")
         self.assertEqual(response.status_code, status)
         return response.json()
 
     def ajax_post(self, *args, **kwargs):
-        return self.ajax_request('post', *args, **kwargs)
+        return self.ajax_request("post", *args, **kwargs)
 
     def ajax_put(self, *args, **kwargs):
-        return self.ajax_request('put', *args, **kwargs)
+        return self.ajax_request("put", *args, **kwargs)
 
     def ajax_delete(self, *args, **kwargs):
-        return self.ajax_request('delete', *args, **kwargs)
+        return self.ajax_request("delete", *args, **kwargs)
 
     def ajax_get(self, *args, **kwargs):
-        return self.ajax_request('get', *args, **kwargs)
+        return self.ajax_request("get", *args, **kwargs)
 
 
 class ModoAPITestCase(ParametersMixin, APITestCase):
@@ -103,4 +102,4 @@ class ModoAPITestCase(ParametersMixin, APITestCase):
     def setUp(self):
         """Setup."""
         super(ModoAPITestCase, self).setUp()
-        self.client.credentials(HTTP_AUTHORIZATION='Token ' + self.token.key)
+        self.client.credentials(HTTP_AUTHORIZATION="Token " + self.token.key)
diff --git a/modoboa/lib/tests/test_email_utils.py b/modoboa/lib/tests/test_email_utils.py
index 274279469..6b2c8bbc4 100644
--- a/modoboa/lib/tests/test_email_utils.py
+++ b/modoboa/lib/tests/test_email_utils.py
@@ -10,7 +10,8 @@ from django.test import SimpleTestCase
 from django.utils.encoding import smart_bytes, smart_text
 
 from ..email_utils import (
-    Email, prepare_addresses, split_address, split_local_part)
+    Email, prepare_addresses, split_address, split_local_part
+)
 
 SAMPLES_DIR = os.path.realpath(
     os.path.join(os.path.dirname(__file__), "sample_messages"))
@@ -64,9 +65,10 @@ class EmailTests(SimpleTestCase):
             EmailTestImplementation("text_plain", links="0")
 
             ex_message = cm.exception.messages
-            self.assertEqual(ex_message,
-                             "links == \"0\" is not valid, did you mean True or "
-                             "False?")
+            self.assertEqual(
+                ex_message,
+                "links == \"0\" is not valid, did you mean True or False?"
+            )
 
     def test_links_value_for_webmail(self):
         """modoboa-webmail sets links = 0 or 1
@@ -105,7 +107,7 @@ class EmailTests(SimpleTestCase):
         self._test_email("multipart", dformat="html", links=True)
 
     def test_email_multipart_without_links(self):
-        """display the text/html part of a multipart message with links removed"""
+        """display the text/html part of a multipart message without links"""
         self._test_email("multipart", dformat="html", links=False)
 
 
diff --git a/modoboa/lib/tests/test_u2u_decode.py b/modoboa/lib/tests/test_u2u_decode.py
index b06bf38c6..9c64cae46 100644
--- a/modoboa/lib/tests/test_u2u_decode.py
+++ b/modoboa/lib/tests/test_u2u_decode.py
@@ -49,12 +49,12 @@ class U2UTestCase(TestCase):
         )
         mailsploit_sample = (
             '"=?utf-8?b?cG90dXNAd2hpdGVob3VzZS5nb3Y=?==?utf-8?Q?=0A=00?="\n'
-            '<=?utf-8?b?cG90dXNAd2hpdGVob3VzZS5nb3Y=?==?utf-8?Q?=0A=00?='
-            '@mailsploit.com>')
+            "<=?utf-8?b?cG90dXNAd2hpdGVob3VzZS5nb3Y=?==?utf-8?Q?=0A=00?="
+            "@mailsploit.com>")
         expected_result = (
-            'potus@whitehouse.gov',
-            '=?utf-8?b?cG90dXNAd2hpdGVob3VzZS5nb3Y=?==?utf-8?Q??='
-            '@mailsploit.com')
+            "potus@whitehouse.gov",
+            "=?utf-8?b?cG90dXNAd2hpdGVob3VzZS5nb3Y=?==?utf-8?Q??="
+            "@mailsploit.com")
         self.assertEqual(
             u2u_decode.decode_address(mailsploit_sample),
             expected_result)
diff --git a/modoboa/lib/u2u_decode.py b/modoboa/lib/u2u_decode.py
index 3d8e97621..5d9367557 100644
--- a/modoboa/lib/u2u_decode.py
+++ b/modoboa/lib/u2u_decode.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """
 Unstructured rfc2047 header to unicode.
@@ -9,9 +9,9 @@ A stupid (and not accurate) answer to https://bugs.python.org/issue1079.
 
 from __future__ import unicode_literals
 
+import re
 from email.header import decode_header, make_header
 from email.utils import parseaddr
-import re
 
 from django.utils.encoding import smart_text
 
diff --git a/modoboa/lib/validators.py b/modoboa/lib/validators.py
index bd5e29918..80bd95ca2 100644
--- a/modoboa/lib/validators.py
+++ b/modoboa/lib/validators.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Field validators."""
 
 from __future__ import unicode_literals
@@ -49,7 +51,8 @@ class UTF8EmailValidator(EmailValidator):
         # dot-atom
         r"^[" + ascii_set + ul + r"]+(\.[" + ascii_set + ul + r"]+)*\Z"
         # quoted-string
-        r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-\011\013\014\016-\177])*"\Z)'
+        r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|'
+        r'\\[\001-\011\013\014\016-\177])*"\Z)'
     )
     user_regex = re.compile(r"(" + user_regex_raw, re.IGNORECASE)
 
diff --git a/modoboa/lib/web_utils.py b/modoboa/lib/web_utils.py
index 2596c94de..8c70f8d51 100644
--- a/modoboa/lib/web_utils.py
+++ b/modoboa/lib/web_utils.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """
 This module contains extra functions/shortcuts used to render HTML.
@@ -29,7 +29,7 @@ def render_actions(actions):
     t = template.Template("""{% load lib_tags %}
 {% for a in actions %}{% render_link a %}{% endfor %}
 """)
-    return t.render(template.Context(dict(actions=actions)))
+    return t.render(template.Context({"actions": actions}))
 
 
 def getctx(status, level=1, callback=None, **kwargs):
@@ -88,7 +88,7 @@ def render_to_json_response(context, **response_kwargs):
     :return: ``HttpResponse`` object
     """
     data = json.dumps(context)
-    response_kwargs['content_type'] = 'application/json'
+    response_kwargs["content_type"] = "application/json"
     return HttpResponse(data, **response_kwargs)
 
 
@@ -136,8 +136,8 @@ class NavigationParameters(object):
     def __init__(self, request, sessionkey):
         self.request = request
         self.sessionkey = sessionkey
-        self.parameters = [('pattern', '', True),
-                           ('criteria', 'from_addr', False)]
+        self.parameters = [("pattern", "", True),
+                           ("criteria", "from_addr", False)]
 
     def __getitem__(self, key):
         """Retrieve an item."""
diff --git a/modoboa/limits/__init__.py b/modoboa/limits/__init__.py
index 990d4c137..01758a791 100644
--- a/modoboa/limits/__init__.py
+++ b/modoboa/limits/__init__.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 default_app_config = "modoboa.limits.apps.LimitsConfig"
diff --git a/modoboa/limits/app_settings.py b/modoboa/limits/app_settings.py
index 9a724e671..070a38f23 100644
--- a/modoboa/limits/app_settings.py
+++ b/modoboa/limits/app_settings.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Custom settings."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/limits/apps.py b/modoboa/limits/apps.py
index 4716d1f19..7f066caf0 100644
--- a/modoboa/limits/apps.py
+++ b/modoboa/limits/apps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """App config for limits."""
 
 from __future__ import unicode_literals
@@ -24,4 +26,4 @@ class LimitsConfig(AppConfig):
     def ready(self):
         load_limits_settings()
 
-        from . import handlers
+        from . import handlers  # NOQA:F401
diff --git a/modoboa/limits/constants.py b/modoboa/limits/constants.py
index f12d5818f..570d961aa 100644
--- a/modoboa/limits/constants.py
+++ b/modoboa/limits/constants.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa limits constants."""
 
 from __future__ import unicode_literals
@@ -6,7 +8,6 @@ import collections
 
 from django.utils.translation import ugettext_lazy as _
 
-
 DEFAULT_USER_LIMITS = collections.OrderedDict((
     ("domains", {
         "content_type": "admin.domain", "label": _("Domains"),
diff --git a/modoboa/limits/forms.py b/modoboa/limits/forms.py
index 3a013a6f2..7b91c377d 100644
--- a/modoboa/limits/forms.py
+++ b/modoboa/limits/forms.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Custom forms."""
 
@@ -8,9 +8,8 @@ from django import forms
 from django.utils.translation import ugettext as _
 
 from modoboa.lib.permissions import get_object_owner
-
-from .lib import allocate_resources_from_user
 from . import utils
+from .lib import allocate_resources_from_user
 
 
 class ResourcePoolForm(forms.Form):
@@ -52,16 +51,16 @@ class ResourcePoolForm(forms.Form):
 
     def save(self):
         owner = get_object_owner(self.account)
-        for name, ltpl in utils.get_user_limit_templates():
+        for name, _definition in utils.get_user_limit_templates():
             fieldname = "{}_limit".format(name)
             if fieldname not in self.cleaned_data:
                 continue
-            l = self.account.userobjectlimit_set.get(name=name)
+            limit = self.account.userobjectlimit_set.get(name=name)
             if not owner.is_superuser:
                 allocate_resources_from_user(
-                    l, owner, self.cleaned_data[fieldname])
-            l.max_value = self.cleaned_data[fieldname]
-            l.save(update_fields=["max_value"])
+                    limit, owner, self.cleaned_data[fieldname])
+            limit.max_value = self.cleaned_data[fieldname]
+            limit.save(update_fields=["max_value"])
 
 
 class DomainLimitsForm(forms.Form):
@@ -94,10 +93,10 @@ class DomainLimitsForm(forms.Form):
 
     def save(self, user, **kwargs):
         """Set limits."""
-        for name, ltpl in utils.get_domain_limit_templates():
+        for name, _definition in utils.get_domain_limit_templates():
             fieldname = "{}_limit".format(name)
             if fieldname not in self.cleaned_data:
                 continue
-            l = self.domain.domainobjectlimit_set.get(name=name)
-            l.max_value = self.cleaned_data[fieldname]
-            l.save()
+            limit = self.domain.domainobjectlimit_set.get(name=name)
+            limit.max_value = self.cleaned_data[fieldname]
+            limit.save()
diff --git a/modoboa/limits/handlers.py b/modoboa/limits/handlers.py
index 8602f2bc6..57309b405 100644
--- a/modoboa/limits/handlers.py
+++ b/modoboa/limits/handlers.py
@@ -1,26 +1,20 @@
+# -*- coding: utf-8 -*-
+
 """Django signal handlers for limits."""
 
 from __future__ import unicode_literals
 
+from django.contrib.contenttypes.models import ContentType
 from django.db.models import signals
 from django.dispatch import receiver
 from django.template.loader import render_to_string
-
-from django.contrib.contenttypes.models import ContentType
 from django.utils.translation import ugettext as _
 
-from modoboa.admin import models as admin_models
-from modoboa.admin import signals as admin_signals
-from modoboa.core import models as core_models
-from modoboa.core import signals as core_signals
-from modoboa.lib import signals as lib_signals
-from modoboa.lib import permissions
+from modoboa.admin import models as admin_models, signals as admin_signals
+from modoboa.core import models as core_models, signals as core_signals
+from modoboa.lib import permissions, signals as lib_signals
 from modoboa.parameters import tools as param_tools
-
-from . import forms
-from . import lib
-from . import models
-from . import utils
+from . import forms, lib, models, utils
 
 
 @receiver(core_signals.can_create_object)
@@ -70,7 +64,7 @@ def create_domain_limits(sender, instance, **kwargs):
     if not kwargs.get("created"):
         return
     global_params = dict(param_tools.get_global_parameters("limits"))
-    for name, definition in utils.get_domain_limit_templates():
+    for name, _definition in utils.get_domain_limit_templates():
         max_value = global_params["deflt_domain_{0}_limit".format(name)]
         models.DomainObjectLimit.objects.create(
             domain=instance, name=name, max_value=max_value)
@@ -275,7 +269,7 @@ def display_pool_usage(sender, user, location, currentpage, **kwargs):
         return []
     return [
         render_to_string("limits/poolusage.html",
-                         dict(limits=limits))
+                         {"limits": limits})
     ]
 
 
diff --git a/modoboa/limits/lib.py b/modoboa/limits/lib.py
index 500cdf454..68dcb734a 100644
--- a/modoboa/limits/lib.py
+++ b/modoboa/limits/lib.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """
 :mod:`lib` --- public functions
 -------------------------------
diff --git a/modoboa/limits/models.py b/modoboa/limits/models.py
index 114a933c6..ce62d9bfc 100644
--- a/modoboa/limits/models.py
+++ b/modoboa/limits/models.py
@@ -1,4 +1,4 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 """Models for the limits extensions."""
 
@@ -11,9 +11,7 @@ from django.utils.functional import cached_property
 from django.utils.translation import ugettext as _
 
 from modoboa.core import models as core_models
-
-from . import lib
-from . import utils
+from . import lib, utils
 
 
 class ObjectLimitMixin(object):
diff --git a/modoboa/limits/serializers.py b/modoboa/limits/serializers.py
index 8b447ad71..9fa0cbd00 100644
--- a/modoboa/limits/serializers.py
+++ b/modoboa/limits/serializers.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Limits serializers."""
 
 from __future__ import unicode_literals
@@ -19,9 +21,10 @@ class ResourcesSerializer(serializers.Serializer):
 
     def to_representation(self, instance):
         """Return limits."""
-        return dict(
+        return [
             (limit.name, limit.max_value)
-            for limit in instance.userobjectlimit_set.all())
+            for limit in instance.userobjectlimit_set.all()
+        ]
 
     def update(self, instance, validated_data):
         """Update limits."""
diff --git a/modoboa/limits/tests/__init__.py b/modoboa/limits/tests/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/limits/tests/__init__.py
+++ b/modoboa/limits/tests/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/limits/tests/test_api.py b/modoboa/limits/tests/test_api.py
index 4707c244b..890c05556 100644
--- a/modoboa/limits/tests/test_api.py
+++ b/modoboa/limits/tests/test_api.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Test cases for the limits extension."""
 
 from __future__ import unicode_literals
@@ -13,9 +14,7 @@ from modoboa.admin.factories import populate_database
 from modoboa.admin.models import Domain
 from modoboa.core import factories as core_factories
 from modoboa.core.models import User
-from modoboa.lib import permissions
-from modoboa.lib import tests as lib_tests
-
+from modoboa.lib import permissions, tests as lib_tests
 from .. import utils
 
 
@@ -23,10 +22,10 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
     """Check that limits are used also by the API."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(APIAdminLimitsTestCase, cls).setUpTestData()
-        for name, tpl in utils.get_user_limit_templates():
+        for name, _definition in utils.get_user_limit_templates():
             cls.localconfig.parameters.set_value(
                 "deflt_user_{0}_limit".format(name), 2)
         cls.localconfig.save()
@@ -41,7 +40,7 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
     def test_domadmins_limit(self):
         """Check domain admins limit."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.r_token.key)
+            HTTP_AUTHORIZATION="Token " + self.r_token.key)
 
         limit = self.reseller.userobjectlimit_set.get(name="domain_admins")
         url = reverse("api:account-list")
@@ -82,7 +81,7 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
     def test_domains_limit(self):
         """Check domains limit."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.r_token.key)
+            HTTP_AUTHORIZATION="Token " + self.r_token.key)
         limit = self.reseller.userobjectlimit_set.get(name="domains")
         quota = self.reseller.userobjectlimit_set.get(name="quota")
         quota.max_value = 3
@@ -104,7 +103,7 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
         response = self.client.post(url, data, format="json")
         self.assertEqual(response.status_code, 403)
         self.assertEqual(
-            response.content.decode('utf-8'), '"Domains: limit reached"'
+            response.content.decode("utf-8"), '"Domains: limit reached"'
         )
 
         self.client.delete(
@@ -120,7 +119,7 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
     def test_domain_aliases_limit(self):
         """Check domain aliases limit."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.r_token.key)
+            HTTP_AUTHORIZATION="Token " + self.r_token.key)
         domain = Domain.objects.get(name="test.com")
         domain.add_admin(self.reseller)
         limit = self.reseller.userobjectlimit_set.get(name="domain_aliases")
@@ -142,7 +141,7 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
     def test_mailboxes_limit(self):
         """Check mailboxes limit."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
 
         limit = self.user.userobjectlimit_set.get(name="mailboxes")
         url = reverse("api:account-list")
@@ -173,7 +172,7 @@ class APIAdminLimitsTestCase(lib_tests.ModoAPITestCase):
     def test_aliases_limit(self):
         """Check mailbox aliases limit."""
         self.client.credentials(
-            HTTP_AUTHORIZATION='Token ' + self.da_token.key)
+            HTTP_AUTHORIZATION="Token " + self.da_token.key)
 
         limit = self.user.userobjectlimit_set.get(name="mailbox_aliases")
         url = reverse("api:alias-list")
@@ -201,12 +200,12 @@ class APIDomainLimitsTestCase(lib_tests.ModoAPITestCase):
     """Check that limits are used also by the API."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(APIDomainLimitsTestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_value(
             "enable_domain_limits", True)
-        for name, tpl in utils.get_domain_limit_templates():
+        for name, _definition in utils.get_domain_limit_templates():
             cls.localconfig.parameters.set_value(
                 "deflt_domain_{0}_limit".format(name), 2)
         cls.localconfig.save()
@@ -266,10 +265,10 @@ class ResourcesAPITestCase(lib_tests.ModoAPITestCase):
     """Check resources API."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(ResourcesAPITestCase, cls).setUpTestData()
-        for name, tpl in utils.get_user_limit_templates():
+        for name, _definition in utils.get_user_limit_templates():
             cls.localconfig.parameters.set_value(
                 "deflt_user_{0}_limit".format(name), 2)
         cls.localconfig.save()
diff --git a/modoboa/limits/tests/test_domain_limits.py b/modoboa/limits/tests/test_domain_limits.py
index 92f6c8749..9442cda99 100644
--- a/modoboa/limits/tests/test_domain_limits.py
+++ b/modoboa/limits/tests/test_domain_limits.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Test cases for the limits extension."""
 
 from __future__ import unicode_literals
@@ -10,7 +11,6 @@ from modoboa.admin.models import Domain
 from modoboa.core import factories as core_factories
 from modoboa.core.models import User
 from modoboa.lib import tests as lib_tests
-
 from .. import utils
 
 
@@ -18,14 +18,14 @@ class DomainLimitsTestCase(lib_tests.ModoTestCase):
     """Per-domain limits tests."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DomainLimitsTestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_values({
             "enable_admin_limits": False,
             "enable_domain_limits": True
         })
-        for name, tpl in utils.get_domain_limit_templates():
+        for name, _definition in utils.get_domain_limit_templates():
             cls.localconfig.parameters.set_value(
                 "deflt_domain_{0}_limit".format(name), 2)
         cls.localconfig.save()
diff --git a/modoboa/limits/tests/test_import.py b/modoboa/limits/tests/test_import.py
index 1b61fd0c5..109021f45 100644
--- a/modoboa/limits/tests/test_import.py
+++ b/modoboa/limits/tests/test_import.py
@@ -1,16 +1,13 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
 from django.core.files.base import ContentFile
 from django.urls import reverse
 
-from modoboa.admin import factories as admin_factories
-from modoboa.admin import models as admin_models
-from modoboa.core import factories as core_factories
-from modoboa.core import models as core_models
+from modoboa.admin import factories as admin_factories, models as admin_models
+from modoboa.core import factories as core_factories, models as core_models
 from modoboa.lib.tests import ModoTestCase
-
 from .. import utils
 
 
@@ -18,7 +15,7 @@ class LimitImportTestCase(ModoTestCase):
     """Base class to test limits."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(LimitImportTestCase, cls).setUpTestData()
         admin_factories.populate_database()
@@ -71,7 +68,7 @@ domainalias; domalias2.com; {domain}; True
         self.assertTrue(limit.is_exceeded())
 
         f = ContentFile("""account; admin3@{domain}; toto; User; One; True; DomainAdmins; admin3@{domain}; 5; {domain}
-""".format(domain=self.domain), name="domain_admins.csv")
+""".format(domain=self.domain), name="domain_admins.csv")  # NOQA:E501
         response = self.client.post(
             reverse("admin:identity_import"), {
                 "sourcefile": f
@@ -135,10 +132,10 @@ alias; alias3@{domain}; True; user@{domain}
 class UserLimitImportTestCase(LimitImportTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         localconfig = core_models.LocalConfig.objects.first()
-        for name, tpl in utils.get_user_limit_templates():
+        for name, _definition in utils.get_user_limit_templates():
             localconfig.parameters.set_value(
                 "deflt_user_{0}_limit".format(name), 2)
         localconfig.save()
@@ -201,14 +198,14 @@ domain; domain3.com; 1000; 100; True
 class DomainLimitImportTestCase(LimitImportTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         localconfig = core_models.LocalConfig.objects.first()
         localconfig.parameters.set_values({
             "enable_domain_limits": True,
             "enable_admin_limits": False
         })
-        for name, tpl in utils.get_domain_limit_templates():
+        for name, _definition in utils.get_domain_limit_templates():
             localconfig.parameters.set_value(
                 "deflt_domain_{0}_limit".format(name), 2)
         localconfig.save()
diff --git a/modoboa/limits/tests/test_user_limits.py b/modoboa/limits/tests/test_user_limits.py
index 39168a24b..41bb40706 100644
--- a/modoboa/limits/tests/test_user_limits.py
+++ b/modoboa/limits/tests/test_user_limits.py
@@ -1,4 +1,5 @@
-# coding: utf-8
+# -*- coding: utf-8 -*-
+
 """Test cases for the limits extension."""
 
 from __future__ import unicode_literals
@@ -10,14 +11,13 @@ from modoboa.admin.models import Alias, Domain
 from modoboa.core.factories import UserFactory
 from modoboa.core.models import User
 from modoboa.lib import tests as lib_tests
-
 from .. import utils
 
 
 class PermissionsTestCase(lib_tests.ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(PermissionsTestCase, cls).setUpTestData()
         populate_database()
@@ -27,11 +27,12 @@ class PermissionsTestCase(lib_tests.ModoTestCase):
 
         Expected result: no.
         """
-        values = dict(
-            username="reseller@test.com", first_name="Reseller", last_name="",
-            password1="Toto1234", password2="Toto1234", role="Resellers",
-            is_active=True, email="reseller@test.com", stepid='step2'
-        )
+        values = {
+            "username": "reseller@test.com", "first_name": "Reseller",
+            "last_name": "", "password1": "Toto1234", "password2": "Toto1234",
+            "role": "Resellers", "is_active": True,
+            "email": "reseller@test.com", "stepid": "step2"
+        }
         self.ajax_post(reverse("admin:account_add"), values)
         account = User.objects.get(username="reseller@test.com")
         self.client.logout()
@@ -46,36 +47,36 @@ class PermissionsTestCase(lib_tests.ModoTestCase):
 class ResourceTestCase(lib_tests.ModoTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Custom setUpTestData method."""
         super(ResourceTestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_values({
             "enable_admin_limits": True,
             "enable_domain_limits": False
         })
-        for name, tpl in utils.get_user_limit_templates():
+        for name, _definition in utils.get_user_limit_templates():
             cls.localconfig.parameters.set_value(
                 "deflt_user_{0}_limit".format(name), 2)
         cls.localconfig.save()
         populate_database()
 
     def _create_account(
-            self, username, role='SimpleUsers', status=200, **kwargs):
-        values = dict(
-            username=username, first_name="Tester", last_name="Toto",
-            password1="Toto1234", password2="Toto1234", role=role,
-            quota_act=True,
-            is_active=True, email=username, stepid='step2',
-        )
+            self, username, role="SimpleUsers", status=200, **kwargs):
+        values = {
+            "username": username, "first_name": "Tester", "last_name": "Toto",
+            "password1": "Toto1234", "password2": "Toto1234", "role": role,
+            "quota_act": True, "is_active": True, "email": username,
+            "stepid": "step2"
+        }
         values.update(kwargs)
         return self.ajax_post(
             reverse("admin:account_add"), values, status
         )
 
-    def _create_alias(self, email, rcpt='user@test.com', status=200):
-        values = dict(
-            address=email, recipients=rcpt, enabled=True
-        )
+    def _create_alias(self, email, rcpt="user@test.com", status=200):
+        values = {
+            "address": email, "recipients": rcpt, "enabled": True
+        }
         return self.ajax_post(
             reverse("admin:alias_add"), values, status
         )
@@ -119,18 +120,18 @@ class ResourceTestCase(lib_tests.ModoTestCase):
         )
 
     def _check_limit(self, name, curvalue, maxvalue):
-        l = self.user.userobjectlimit_set.get(name=name)
-        self.assertEqual(l.current_value, curvalue)
-        self.assertEqual(l.max_value, maxvalue)
+        limit = self.user.userobjectlimit_set.get(name=name)
+        self.assertEqual(limit.current_value, curvalue)
+        self.assertEqual(limit.max_value, maxvalue)
 
 
 class DomainAdminTestCase(ResourceTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(DomainAdminTestCase, cls).setUpTestData()
-        cls.user = User.objects.get(username='admin@test.com')
+        cls.user = User.objects.get(username="admin@test.com")
         cls.user.userobjectlimit_set.filter(
             name__in=["mailboxes", "mailbox_aliases"]).update(max_value=2)
 
@@ -140,64 +141,64 @@ class DomainAdminTestCase(ResourceTestCase):
         self.client.force_login(self.user)
 
     def test_mailboxes_limit(self):
-        self._create_account('tester1@test.com')
-        self._check_limit('mailboxes', 1, 2)
-        self._create_account('tester2@test.com')
-        self._check_limit('mailboxes', 2, 2)
-        self._create_account('tester3@test.com', status=403)
-        self._check_limit('mailboxes', 2, 2)
+        self._create_account("tester1@test.com")
+        self._check_limit("mailboxes", 1, 2)
+        self._create_account("tester2@test.com")
+        self._check_limit("mailboxes", 2, 2)
+        self._create_account("tester3@test.com", status=403)
+        self._check_limit("mailboxes", 2, 2)
         self.ajax_post(
-            reverse('admin:account_delete',
-                    args=[User.objects.get(username='tester2@test.com').id]),
+            reverse("admin:account_delete",
+                    args=[User.objects.get(username="tester2@test.com").id]),
             {}
         )
-        self._check_limit('mailboxes', 1, 2)
+        self._check_limit("mailboxes", 1, 2)
 
     def test_aliases_limit(self):
-        self._create_alias('alias1@test.com')
-        self._check_limit('mailbox_aliases', 1, 2)
-        self._create_alias('alias2@test.com')
-        self._check_limit('mailbox_aliases', 2, 2)
-        self._create_alias('alias3@test.com', status=403)
-        self._check_limit('mailbox_aliases', 2, 2)
+        self._create_alias("alias1@test.com")
+        self._check_limit("mailbox_aliases", 1, 2)
+        self._create_alias("alias2@test.com")
+        self._check_limit("mailbox_aliases", 2, 2)
+        self._create_alias("alias3@test.com", status=403)
+        self._check_limit("mailbox_aliases", 2, 2)
         # Set unlimited value
         self.user.userobjectlimit_set.filter(name="mailbox_aliases").update(
             max_value=-1)
-        self._create_alias('alias3@test.com')
-        self._check_limit('mailbox_aliases', 3, -1)
+        self._create_alias("alias3@test.com")
+        self._check_limit("mailbox_aliases", 3, -1)
         self.ajax_post(
-            reverse('admin:alias_delete') + '?selection=%d'
-            % Alias.objects.get(address='alias2@test.com').id,
+            reverse("admin:alias_delete") + "?selection=%d"
+            % Alias.objects.get(address="alias2@test.com").id,
             {}
         )
-        self._check_limit('mailbox_aliases', 2, -1)
+        self._check_limit("mailbox_aliases", 2, -1)
 
     def test_aliases_limit_through_account_form(self):
-        user = User.objects.get(username='user@test.com')
-        values = dict(
-            username=user.username, role=user.role,
-            is_active=user.is_active, email=user.email, quota_act=True,
-            aliases="alias1@test.com", aliases_1="alias2@test.com",
-            language="en"
-        )
+        user = User.objects.get(username="user@test.com")
+        values = {
+            "username": user.username, "role": user.role,
+            "is_active": user.is_active, "email": user.email, "quota_act": True,
+            "aliases": "alias1@test.com", "aliases_1": "alias2@test.com",
+            "language": "en"
+        }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
         )
-        Alias.objects.get(address='alias1@test.com')
-        self._check_limit('mailbox_aliases', 2, 2)
+        Alias.objects.get(address="alias1@test.com")
+        self._check_limit("mailbox_aliases", 2, 2)
 
 
 class ResellerTestCase(ResourceTestCase):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(ResellerTestCase, cls).setUpTestData()
         cls.localconfig.parameters.set_value("deflt_user_quota_limit", 1000)
         cls.localconfig.save()
         cls.user = UserFactory(
-            username='reseller', groups=('Resellers',)
+            username="reseller", groups=("Resellers",)
         )
 
     def setUp(self):
@@ -209,32 +210,32 @@ class ResellerTestCase(ResourceTestCase):
         response = self.client.get(reverse("admin:domain_list"))
         self.assertContains(response, "Domains (0%)")
         self.assertContains(response, "Domain aliases (0%)")
-        self._create_domain('domain1.tld')
-        self._check_limit('domains', 1, 2)
-        self._create_domain('domain2.tld')
-        self._check_limit('domains', 2, 2)
-        self._create_domain('domain3.tld', 403)
-        self._check_limit('domains', 2, 2)
+        self._create_domain("domain1.tld")
+        self._check_limit("domains", 1, 2)
+        self._create_domain("domain2.tld")
+        self._check_limit("domains", 2, 2)
+        self._create_domain("domain3.tld", 403)
+        self._check_limit("domains", 2, 2)
         self.ajax_post(
-            reverse('admin:domain_delete',
-                    args=[Domain.objects.get(name='domain2.tld').id]),
+            reverse("admin:domain_delete",
+                    args=[Domain.objects.get(name="domain2.tld").id]),
             {}
         )
-        self._check_limit('domains', 1, 2)
+        self._check_limit("domains", 1, 2)
 
     def test_domain_aliases_limit(self):
-        self._create_domain('pouet.com')
-        self._domain_alias_operation('add', 'pouet.com', 'domain-alias1.tld')
-        self._check_limit('domain_aliases', 1, 2)
-        self._domain_alias_operation('add', 'pouet.com', 'domain-alias2.tld')
-        self._check_limit('domain_aliases', 2, 2)
+        self._create_domain("pouet.com")
+        self._domain_alias_operation("add", "pouet.com", "domain-alias1.tld")
+        self._check_limit("domain_aliases", 1, 2)
+        self._domain_alias_operation("add", "pouet.com", "domain-alias2.tld")
+        self._check_limit("domain_aliases", 2, 2)
         self._domain_alias_operation(
-            'add', 'pouet.com', 'domain-alias3.tld', 403
+            "add", "pouet.com", "domain-alias3.tld", 403
         )
-        self._check_limit('domain_aliases', 2, 2)
+        self._check_limit("domain_aliases", 2, 2)
         self._domain_alias_operation(
-            'delete', 'pouet.com', 'domain-alias2.tld')
-        self._check_limit('domain_aliases', 1, 2)
+            "delete", "pouet.com", "domain-alias2.tld")
+        self._check_limit("domain_aliases", 1, 2)
 
     def test_domain_admins_limit(self):
         response = self.client.get(reverse("admin:identity_list"))
@@ -242,21 +243,21 @@ class ResellerTestCase(ResourceTestCase):
         self.assertContains(response, "Mailboxes (0%)")
         self.assertContains(response, "Mailbox aliases (0%)")
 
-        self._create_domain('domain.tld')
-        self._create_account('admin1@domain.tld', role='DomainAdmins')
-        self._check_limit('domain_admins', 1, 2)
-        self._create_account('admin2@domain.tld', role='DomainAdmins')
-        self._check_limit('domain_admins', 2, 2)
+        self._create_domain("domain.tld")
+        self._create_account("admin1@domain.tld", role="DomainAdmins")
+        self._check_limit("domain_admins", 1, 2)
+        self._create_account("admin2@domain.tld", role="DomainAdmins")
+        self._check_limit("domain_admins", 2, 2)
         resp = self._create_account(
-            'admin3@domain.tld',
-            role='DomainAdmins',
+            "admin3@domain.tld",
+            role="DomainAdmins",
             status=400)
         self.assertEqual(
-            resp['form_errors']['role'][0],
-            'Select a valid choice. DomainAdmins is not one of the available '
-            'choices.'
+            resp["form_errors"]["role"][0],
+            "Select a valid choice. DomainAdmins is not one of the available "
+            "choices."
         )
-        self._check_limit('domain_admins', 2, 2)
+        self._check_limit("domain_admins", 2, 2)
 
         self.user.userobjectlimit_set.filter(
             name="mailboxes").update(max_value=3)
@@ -272,17 +273,17 @@ class ResellerTestCase(ResourceTestCase):
             values, status=400
         )
         self.assertEqual(
-            resp['form_errors']['role'][0],
-            'Select a valid choice. DomainAdmins is not one of the available '
-            'choices.'
+            resp["form_errors"]["role"][0],
+            "Select a valid choice. DomainAdmins is not one of the available "
+            "choices."
         )
-        self._check_limit('domain_admins', 2, 2)
+        self._check_limit("domain_admins", 2, 2)
 
     def test_domain_admin_resource_are_empty(self):
-        self._create_domain('domain.tld')
-        self._create_account('admin1@domain.tld', role='DomainAdmins')
-        domadmin = User.objects.get(username='admin1@domain.tld')
-        for l in ['mailboxes', 'mailbox_aliases']:
+        self._create_domain("domain.tld")
+        self._create_account("admin1@domain.tld", role="DomainAdmins")
+        domadmin = User.objects.get(username="admin1@domain.tld")
+        for l in ["mailboxes", "mailbox_aliases"]:
             self.assertEqual(
                 domadmin.userobjectlimit_set.get(name=l).max_value, 0
             )
@@ -290,13 +291,13 @@ class ResellerTestCase(ResourceTestCase):
     def test_domain_admins_limit_from_domain_tpl(self):
         self.user.userobjectlimit_set.filter(
             name="domains").update(max_value=3)
-        self._create_domain('domain1.tld', withtpl=True)
-        self._create_domain('domain2.tld', withtpl=True)
-        self._check_limit('domain_admins', 2, 2)
-        self._check_limit('domains', 2, 3)
-        self._create_domain('domain3.tld', status=200, withtpl=True)
-        self._check_limit('domain_admins', 2, 2)
-        self._check_limit('domains', 3, 3)
+        self._create_domain("domain1.tld", withtpl=True)
+        self._create_domain("domain2.tld", withtpl=True)
+        self._check_limit("domain_admins", 2, 2)
+        self._check_limit("domains", 2, 3)
+        self._create_domain("domain3.tld", status=200, withtpl=True)
+        self._check_limit("domain_admins", 2, 2)
+        self._check_limit("domains", 3, 3)
 
     def test_quota(self):
         """Check quota resource."""
@@ -353,51 +354,51 @@ class ResellerTestCase(ResourceTestCase):
 
     def test_reseller_deletes_domain(self):
         """Check if all resources are restored after the deletion."""
-        self._create_domain('domain.tld', withtpl=True)
+        self._create_domain("domain.tld", withtpl=True)
         dom = Domain.objects.get(name="domain.tld")
         self.ajax_post(
             reverse("admin:domain_delete", args=[dom.id]),
             {}
         )
-        self._check_limit('domains', 0, 2)
-        self._check_limit('domain_admins', 1, 2)
-        self._check_limit('mailboxes', 0, 2)
-        self._check_limit('mailbox_aliases', 0, 2)
+        self._check_limit("domains", 0, 2)
+        self._check_limit("domain_admins", 1, 2)
+        self._check_limit("mailboxes", 0, 2)
+        self._check_limit("mailbox_aliases", 0, 2)
 
     def test_sadmin_removes_ownership(self):
-        self._create_domain('domain.tld', withtpl=True)
+        self._create_domain("domain.tld", withtpl=True)
         dom = Domain.objects.get(name="domain.tld")
         self.client.logout()
-        self.client.login(username='admin', password='password')
+        self.client.login(username="admin", password="password")
         self.ajax_get(
             "{0}?domid={1}&daid={2}".format(
-                reverse('admin:permission_remove'),
+                reverse("admin:permission_remove"),
                 dom.id, self.user.id
             ), {}
         )
-        self._check_limit('domains', 0, 2)
-        self._check_limit('domain_admins', 0, 2)
-        self._check_limit('mailboxes', 0, 2)
-        self._check_limit('mailbox_aliases', 0, 2)
+        self._check_limit("domains", 0, 2)
+        self._check_limit("domain_admins", 0, 2)
+        self._check_limit("mailboxes", 0, 2)
+        self._check_limit("mailbox_aliases", 0, 2)
 
     def test_allocate_from_pool(self):
-        self._create_domain('domain.tld')
-        self._create_account('admin1@domain.tld', role='DomainAdmins')
-        user = User.objects.get(username='admin1@domain.tld')
+        self._create_domain("domain.tld")
+        self._create_account("admin1@domain.tld", role="DomainAdmins")
+        user = User.objects.get(username="admin1@domain.tld")
 
         # Give 1 mailbox and 2 aliases to the admin -> should work
         values = {
-            'username': user.username, 'role': user.role, 'quota_act': True,
-            'is_active': user.is_active, 'email': user.email,
-            'mailboxes_limit': 1, 'mailbox_aliases_limit': 2,
-            'language': 'en'
+            "username": user.username, "role": user.role, "quota_act": True,
+            "is_active": user.is_active, "email": user.email,
+            "mailboxes_limit": 1, "mailbox_aliases_limit": 2,
+            "language": "en"
         }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
         )
-        self._check_limit('mailboxes', 1, 1)
-        self._check_limit('mailbox_aliases', 0, 0)
+        self._check_limit("mailboxes", 1, 1)
+        self._check_limit("mailbox_aliases", 0, 0)
 
         # Delete the admin -> resources should go back to the
         # reseller's pool
@@ -405,20 +406,20 @@ class ResellerTestCase(ResourceTestCase):
             reverse("admin:account_delete", args=[user.id]),
             {}
         )
-        self._check_limit('mailboxes', 0, 2)
-        self._check_limit('mailbox_aliases', 0, 2)
+        self._check_limit("mailboxes", 0, 2)
+        self._check_limit("mailbox_aliases", 0, 2)
 
     def test_restore_resources(self):
         """Give resource to a domain admin and restore them."""
-        self._create_domain('domain.tld')
-        dom = Domain.objects.get(name='domain.tld')
-        self._create_account('admin1@domain.tld', role='DomainAdmins')
-        user = User.objects.get(username='admin1@domain.tld')
+        self._create_domain("domain.tld")
+        dom = Domain.objects.get(name="domain.tld")
+        self._create_account("admin1@domain.tld", role="DomainAdmins")
+        user = User.objects.get(username="admin1@domain.tld")
         values = {
-            'username': user.username, 'role': user.role, 'quota_act': True,
-            'is_active': user.is_active, 'email': user.email,
-            'mailboxes_limit': 1, 'mailbox_aliases_limit': 2,
-            'language': 'en'
+            "username": user.username, "role": user.role, "quota_act": True,
+            "is_active": user.is_active, "email": user.email,
+            "mailboxes_limit": 1, "mailbox_aliases_limit": 2,
+            "language": "en"
         }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
@@ -426,71 +427,71 @@ class ResellerTestCase(ResourceTestCase):
         )
         dom.add_admin(user)
         self.client.logout()
-        self.client.login(username='admin1@domain.tld', password='Toto1234')
-        self._create_account('user1@domain.tld')
-        self._create_alias('alias1@domain.tld', 'user1@domain.tld')
-        self._create_alias('alias2@domain.tld', 'user1@domain.tld')
+        self.client.login(username="admin1@domain.tld", password="Toto1234")
+        self._create_account("user1@domain.tld")
+        self._create_alias("alias1@domain.tld", "user1@domain.tld")
+        self._create_alias("alias2@domain.tld", "user1@domain.tld")
         self.client.logout()
-        self.client.login(username='reseller', password='toto')
+        self.client.login(username="reseller", password="toto")
         # Delete the admin -> resources should go back to the
         # reseller's pool
         self.ajax_post(
             reverse("admin:account_delete", args=[user.id]),
             {}
         )
-        self._check_limit('mailboxes', 1, 2)
-        self._check_limit('mailbox_aliases', 2, 2)
+        self._check_limit("mailboxes", 1, 2)
+        self._check_limit("mailbox_aliases", 2, 2)
 
     def test_change_role(self):
-        self._create_domain('domain.tld')
-        self._create_account('admin1@domain.tld', role='DomainAdmins')
-        user = User.objects.get(username='admin1@domain.tld')
+        self._create_domain("domain.tld")
+        self._create_account("admin1@domain.tld", role="DomainAdmins")
+        user = User.objects.get(username="admin1@domain.tld")
 
         # Give 1 mailbox and 2 aliases to the admin -> should work
         values = {
-            'username': user.username, 'role': user.role, 'quota_act': True,
-            'is_active': user.is_active, 'email': user.email,
-            'mailboxes_limit': 1, 'mailbox_aliases_limit': 2,
-            'language': 'en'
+            "username": user.username, "role": user.role, "quota_act": True,
+            "is_active": user.is_active, "email": user.email,
+            "mailboxes_limit": 1, "mailbox_aliases_limit": 2,
+            "language": "en"
         }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
         )
-        self._check_limit('mailboxes', 1, 1)
-        self._check_limit('mailbox_aliases', 0, 0)
+        self._check_limit("mailboxes", 1, 1)
+        self._check_limit("mailbox_aliases", 0, 0)
 
         # Change admin role to SimpleUser -> resources should go back
         # to the reseller.
         values = {
-            'username': user.username, 'role': 'SimpleUsers',
-            'quota_act': True,
-            'is_active': user.is_active, 'email': user.email,
-            'language': 'en',
+            "username": user.username, "role": "SimpleUsers",
+            "quota_act": True,
+            "is_active": user.is_active, "email": user.email,
+            "language": "en",
         }
         self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values
         )
-        self._check_limit('mailboxes', 1, 2)
-        self._check_limit('mailbox_aliases', 0, 2)
+        self._check_limit("mailboxes", 1, 2)
+        self._check_limit("mailbox_aliases", 0, 2)
 
     def test_allocate_too_much(self):
-        self._create_domain('domain.tld')
-        self._create_account('admin1@domain.tld', role='DomainAdmins')
-        user = User.objects.get(username='admin1@domain.tld')
+        self._create_domain("domain.tld")
+        self._create_account("admin1@domain.tld", role="DomainAdmins")
+        user = User.objects.get(username="admin1@domain.tld")
 
         # Give 2 mailboxes and 3 aliases to the admin -> should fail.
         values = {
-            'username': user.username, 'role': user.role, 'quota_act': True,
-            'is_active': user.is_active, 'email': user.email,
-            'mailboxes_limit': 2, 'mailbox_aliases_limit': 3,
-            'language': 'en'
+            "username": user.username, "role": user.role, "quota_act": True,
+            "is_active": user.is_active, "email": user.email,
+            "mailboxes_limit": 2, "mailbox_aliases_limit": 3,
+            "language": "en"
         }
         resp = self.ajax_post(
             reverse("admin:account_change", args=[user.id]),
             values, 424
         )
-        self.assertEqual(resp, 'Not enough resources')
-        self._check_limit('mailboxes', 1, 2)
-        self._check_limit('mailbox_aliases', 0, 2)
+        self.assertEqual(resp, "Not enough resources")
+        self._check_limit("mailboxes", 1, 2)
+        self._check_limit("mailbox_aliases", 0, 2)
diff --git a/modoboa/limits/urls_api.py b/modoboa/limits/urls_api.py
index dad167523..8295e069f 100644
--- a/modoboa/limits/urls_api.py
+++ b/modoboa/limits/urls_api.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Limits API urls."""
 
 from __future__ import unicode_literals
@@ -6,7 +8,6 @@ from rest_framework import routers
 
 from . import viewsets
 
-
 router = routers.SimpleRouter()
 router.register(
     r"resources", viewsets.ResourcesViewSet, base_name="resources")
diff --git a/modoboa/limits/utils.py b/modoboa/limits/utils.py
index 265a579ca..ebbb11972 100644
--- a/modoboa/limits/utils.py
+++ b/modoboa/limits/utils.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Modoboa limits utilities."""
 
 from __future__ import unicode_literals
@@ -21,10 +23,10 @@ def move_pool_resource(owner, user):
     When an account doesn't need a pool anymore, we move the
     associated resource to the pool of its owner.
     """
-    for name, ltpl in get_user_limit_templates():
-        l = user.userobjectlimit_set.get(name=name)
-        if l.max_value < 0:
+    for name, _definition in get_user_limit_templates():
+        user_limit = user.userobjectlimit_set.get(name=name)
+        if user_limit.max_value < 0:
             continue
-        ol = owner.userobjectlimit_set.get(name=name)
-        ol.max_value += l.max_value
-        ol.save()
+        owner_limit = owner.userobjectlimit_set.get(name=name)
+        owner_limit.max_value += user_limit.max_value
+        owner_limit.save()
diff --git a/modoboa/limits/views.py b/modoboa/limits/views.py
deleted file mode 100644
index e17c22b7f..000000000
--- a/modoboa/limits/views.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# coding: utf-8
-
-from __future__ import unicode_literals
diff --git a/modoboa/limits/viewsets.py b/modoboa/limits/viewsets.py
index 2d792ca75..7cb8b3e55 100644
--- a/modoboa/limits/viewsets.py
+++ b/modoboa/limits/viewsets.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Limits API."""
 
 from __future__ import unicode_literals
@@ -5,10 +7,9 @@ from __future__ import unicode_literals
 from django.contrib.contenttypes.models import ContentType
 
 from rest_framework import mixins, viewsets
-from rest_framework.permissions import IsAuthenticated, DjangoModelPermissions
+from rest_framework.permissions import DjangoModelPermissions, IsAuthenticated
 
 from modoboa.core import models as core_models
-
 from . import serializers
 
 
diff --git a/modoboa/parameters/__init__.py b/modoboa/parameters/__init__.py
index baffc4882..e69de29bb 100644
--- a/modoboa/parameters/__init__.py
+++ b/modoboa/parameters/__init__.py
@@ -1 +0,0 @@
-from __future__ import unicode_literals
diff --git a/modoboa/parameters/apps.py b/modoboa/parameters/apps.py
index cbf060639..f60d64f47 100644
--- a/modoboa/parameters/apps.py
+++ b/modoboa/parameters/apps.py
@@ -1,7 +1,9 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from django.apps import AppConfig
 
 
 class ParametersConfig(AppConfig):
-    name = 'parameters'
+    name = "parameters"
diff --git a/modoboa/parameters/forms.py b/modoboa/parameters/forms.py
index d26996e13..19243c7b0 100644
--- a/modoboa/parameters/forms.py
+++ b/modoboa/parameters/forms.py
@@ -1,11 +1,12 @@
+# -*- coding: utf-8 -*-
+
 """Parameters forms."""
 
 from __future__ import unicode_literals
 
 from django import forms
 
-from modoboa.lib import db_utils
-from modoboa.lib import form_utils
+from modoboa.lib import db_utils, form_utils
 
 
 class GenericParametersForm(forms.Form):
@@ -71,7 +72,7 @@ class AdminParametersForm(GenericParametersForm):
         """Save parameters to database."""
         parameters = {}
         for name, value in list(self.cleaned_data.items()):
-            if type(self.fields[name]) is form_utils.SeparatorField:
+            if isinstance(self.fields[name], form_utils.SeparatorField):
                 continue
             parameters[name] = value
         self.localconfig.parameters.set_values(parameters, app=self.app)
@@ -102,7 +103,7 @@ class UserParametersForm(GenericParametersForm):
         """Save new values."""
         parameters = {}
         for name, value in list(self.cleaned_data.items()):
-            if type(self.fields[name]) is form_utils.SeparatorField:
+            if isinstance(self.fields[name], form_utils.SeparatorField):
                 continue
             parameters[name] = value
         self.user.parameters.set_values(parameters, app=self.app)
diff --git a/modoboa/parameters/tests.py b/modoboa/parameters/tests.py
deleted file mode 100644
index 36fcdafd1..000000000
--- a/modoboa/parameters/tests.py
+++ /dev/null
@@ -1,5 +0,0 @@
-from __future__ import unicode_literals
-
-from django.test import TestCase
-
-# Create your tests here.
diff --git a/modoboa/parameters/tools.py b/modoboa/parameters/tools.py
index 383b17442..5187ec0a5 100644
--- a/modoboa/parameters/tools.py
+++ b/modoboa/parameters/tools.py
@@ -1,12 +1,12 @@
+# -*- coding: utf-8 -*-
+
 """Parameters management."""
 
 from __future__ import unicode_literals
 
 import copy
 
-from modoboa.lib import exceptions
-from modoboa.lib import form_utils
-from modoboa.lib import signals
+from modoboa.lib import exceptions, form_utils, signals
 from modoboa.lib.sysutils import guess_extension_name
 
 
@@ -44,10 +44,10 @@ class Registry(object):
 
     def _load_default_values(self, level):
         """Load default values."""
-        for app, data in list(self._registry[level].items()):
+        for _app, data in list(self._registry[level].items()):
             form = data["formclass"](load_values_from_db=False)
             for name, field in list(form.fields.items()):
-                if type(field) is form_utils.SeparatorField:
+                if isinstance(field, form_utils.SeparatorField):
                     continue
                 data["defaults"][name] = field.initial
 
@@ -58,8 +58,10 @@ class Registry(object):
         if first_app in self._registry[level]:
             sorted_apps.append(first_app)
         sorted_apps += sorted(
-            [a for a in list(self._registry[level].keys())
-             if a != first_app],
+            (
+                a for a in self._registry[level]
+                if a != first_app
+            ),
             key=lambda a: self._registry[level][a]["label"]
         )
         result = []
@@ -96,6 +98,7 @@ class Registry(object):
             raise NotDefined(app)
         return self._registry[level][app]["defaults"]
 
+
 registry = Registry()
 
 
diff --git a/modoboa/relaydomains/__init__.py b/modoboa/relaydomains/__init__.py
index c9afa7d7b..05dc26897 100644
--- a/modoboa/relaydomains/__init__.py
+++ b/modoboa/relaydomains/__init__.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 default_app_config = "modoboa.relaydomains.apps.RelayDomainsConfig"
diff --git a/modoboa/relaydomains/apps.py b/modoboa/relaydomains/apps.py
index 8a0236773..cfdb726b3 100644
--- a/modoboa/relaydomains/apps.py
+++ b/modoboa/relaydomains/apps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """AppConfig for relaydomains."""
 
 from __future__ import unicode_literals
@@ -13,5 +15,5 @@ class RelayDomainsConfig(AppConfig):
     verbose_name = "Modoboa relay domains"
 
     def ready(self):
-        from . import handlers
-        from . import transport
+        from . import handlers  # NOQA:F401
+        from . import transport  # NOQA:F401
diff --git a/modoboa/relaydomains/forms.py b/modoboa/relaydomains/forms.py
index 5aa128ff8..87c728d62 100644
--- a/modoboa/relaydomains/forms.py
+++ b/modoboa/relaydomains/forms.py
@@ -1,10 +1,11 @@
+# -*- coding: utf-8 -*-
+
 """Postfix relay domains extension forms."""
 
 from __future__ import unicode_literals
 
 from modoboa.lib.form_utils import WizardStep
-from modoboa.transport import forms as tr_forms
-from modoboa.transport import models as tr_models
+from modoboa.transport import forms as tr_forms, models as tr_models
 
 
 class RelayDomainWizardStep(WizardStep):
diff --git a/modoboa/relaydomains/handlers.py b/modoboa/relaydomains/handlers.py
index 75ab11b61..b06effa28 100644
--- a/modoboa/relaydomains/handlers.py
+++ b/modoboa/relaydomains/handlers.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Django signal handlers for relaydomains."""
 
 from __future__ import unicode_literals
@@ -6,16 +8,11 @@ from django.db.models import signals
 from django.dispatch import receiver
 from django.utils.translation import ugettext as _
 
-from modoboa.admin import models as admin_models
-from modoboa.admin import signals as admin_signals
+from modoboa.admin import models as admin_models, signals as admin_signals
 from modoboa.core import signals as core_signals
 from modoboa.lib.email_utils import split_mailbox
 from modoboa.transport import models as tr_models
-
-from . import forms
-from . import lib
-from . import models
-from . import postfix_maps
+from . import forms, lib, models, postfix_maps
 
 
 @receiver(admin_signals.use_external_recipients)
diff --git a/modoboa/relaydomains/lib.py b/modoboa/relaydomains/lib.py
index e812ffb27..bcebef70b 100644
--- a/modoboa/relaydomains/lib.py
+++ b/modoboa/relaydomains/lib.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Internal library."""
 
 from __future__ import unicode_literals
@@ -6,8 +8,7 @@ from django.utils.translation import ugettext as _
 
 from modoboa.admin import models as admin_models
 from modoboa.lib.exceptions import BadRequest
-from modoboa.transport import backends as tr_backends
-from modoboa.transport import models as tr_models
+from modoboa.transport import backends as tr_backends, models as tr_models
 
 
 def import_relaydomain(user, row, formopts):
diff --git a/modoboa/relaydomains/models.py b/modoboa/relaydomains/models.py
index 75e8fb312..5e3700c78 100644
--- a/modoboa/relaydomains/models.py
+++ b/modoboa/relaydomains/models.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Relay domain related models."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/relaydomains/postfix_maps.py b/modoboa/relaydomains/postfix_maps.py
index d0440337f..77c5904e0 100644
--- a/modoboa/relaydomains/postfix_maps.py
+++ b/modoboa/relaydomains/postfix_maps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Map file definitions for postfix."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/relaydomains/serializers.py b/modoboa/relaydomains/serializers.py
index 9c86efff8..8887f2714 100644
--- a/modoboa/relaydomains/serializers.py
+++ b/modoboa/relaydomains/serializers.py
@@ -1,5 +1,9 @@
+# -*- coding: utf-8 -*-
+
 """RelayDomain serializers."""
 
+from __future__ import unicode_literals
+
 import json
 
 from django.utils.translation import ugettext as _
@@ -7,8 +11,7 @@ from django.utils.translation import ugettext as _
 from rest_framework import serializers
 
 from modoboa.admin import models as admin_models
-from modoboa.transport import backends as tr_backends
-from modoboa.transport import models as tr_models
+from modoboa.transport import backends as tr_backends, models as tr_models
 
 
 class TransportSerializer(serializers.ModelSerializer):
@@ -42,7 +45,11 @@ class RelayDomainSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = admin_models.Domain
-        fields = ("pk", "name", "enabled", "transport")
+        fields = (
+            "pk", "name", "enabled", "transport", "enable_dkim",
+            "dkim_key_selector", "dkim_public_key"
+        )
+        read_only_fields = ("pk", "dkim_public_key", )
 
     def create(self, validated_data):
         """Use backend to serialize data."""
diff --git a/modoboa/relaydomains/tests.py b/modoboa/relaydomains/tests.py
index 4f8ddecb7..ca828e5ce 100644
--- a/modoboa/relaydomains/tests.py
+++ b/modoboa/relaydomains/tests.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """relaydomains unit tests."""
 
 from __future__ import unicode_literals
@@ -5,18 +7,15 @@ from __future__ import unicode_literals
 import json
 
 from django.core.files.base import ContentFile
-from django.urls import reverse
 from django.test import TestCase
+from django.urls import reverse
 
-from modoboa.admin import factories as admin_factories
-from modoboa.admin import models as admin_models
+from modoboa.admin import factories as admin_factories, models as admin_models
 from modoboa.core.factories import UserFactory
-from modoboa.lib.tests import ModoAPITestCase, ModoTestCase
 from modoboa.lib.test_utils import MapFilesTestCaseMixin
+from modoboa.lib.tests import ModoAPITestCase, ModoTestCase
 from modoboa.limits import utils as limits_utils
-from modoboa.transport import factories as tr_factories
-from modoboa.transport import models as tr_models
-
+from modoboa.transport import factories as tr_factories, models as tr_models
 from . import models
 
 
@@ -53,12 +52,12 @@ class Operations(object):
             "default_mailbox_quota": domain.default_mailbox_quota
         }
         aliases = [alias.name for alias in domain.domainalias_set.all()]
-        if optype == 'add':
+        if optype == "add":
             aliases.append(name)
         else:
             aliases.remove(name)
         for cpt, alias in enumerate(aliases):
-            fname = 'aliases' if not cpt else 'aliases_%d' % cpt
+            fname = "aliases" if not cpt else "aliases_%d" % cpt
             values[fname] = alias
         return self.ajax_post(
             reverse("admin:domain_change",
@@ -67,15 +66,15 @@ class Operations(object):
         )
 
     def _check_limit(self, name, curvalue, maxvalue):
-        l = self.user.userobjectlimit_set.get(name=name)
-        self.assertEqual(l.current_value, curvalue)
-        self.assertEqual(l.max_value, maxvalue)
+        limit = self.user.userobjectlimit_set.get(name=name)
+        self.assertEqual(limit.current_value, curvalue)
+        self.assertEqual(limit.max_value, maxvalue)
 
 
 class RelayDomainsTestCase(ModoTestCase, Operations):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(RelayDomainsTestCase, cls).setUpTestData()
         admin_factories.populate_database()
@@ -115,20 +114,20 @@ class RelayDomainsTestCase(ModoTestCase, Operations):
 
         FIXME: add a check for domain alias.
         """
-        self._create_relay_domain('relaydomain1.tld')
-        transport = tr_models.Transport.objects.get(pattern='relaydomain1.tld')
+        self._create_relay_domain("relaydomain1.tld")
+        transport = tr_models.Transport.objects.get(pattern="relaydomain1.tld")
         self.assertEqual(
-            transport._settings["relay_target_host"], 'external.host.tld')
+            transport._settings["relay_target_host"], "external.host.tld")
         self.assertEqual(
             transport._settings["relay_verify_recipients"], False)
 
-        resp = self._create_relay_domain('test.com', 400)
-        self.assertEqual(resp['form_errors']['name'][0],
-                         'Domain with this Name already exists.')
-        resp = self._create_relay_domain('relaydomainalias.tld', 400)
+        resp = self._create_relay_domain("test.com", 400)
+        self.assertEqual(resp["form_errors"]["name"][0],
+                         "Domain with this Name already exists.")
+        resp = self._create_relay_domain("relaydomainalias.tld", 400)
         self.assertEqual(
-            resp['form_errors']['name'][0],
-            'A domain alias with this name already exists'
+            resp["form_errors"]["name"][0],
+            "A domain alias with this name already exists"
         )
 
     def test_create_relaydomainalias(self):
@@ -140,21 +139,21 @@ class RelayDomainsTestCase(ModoTestCase, Operations):
         FIXME: add a check for domain alias.
         """
         self._relay_domain_alias_operation(
-            'add', self.dom, 'relaydomainalias1.tld'
+            "add", self.dom, "relaydomainalias1.tld"
         )
         resp = self._relay_domain_alias_operation(
-            'add', self.dom, 'test.com', 400
+            "add", self.dom, "test.com", 400
         )
         self.assertEqual(
-            resp['form_errors']['aliases_2'][0],
-            'A domain with this name already exists'
+            resp["form_errors"]["aliases_2"][0],
+            "A domain with this name already exists"
         )
         resp = self._relay_domain_alias_operation(
-            'add', self.dom, self.dom.name, 400
+            "add", self.dom, self.dom.name, 400
         )
         self.assertEqual(
-            resp['form_errors']['aliases_2'][0],
-            'A domain with this name already exists'
+            resp["form_errors"]["aliases_2"][0],
+            "A domain with this name already exists"
         )
 
     def test_edit_relaydomain(self):
@@ -238,12 +237,12 @@ class RelayDomainsTestCase(ModoTestCase, Operations):
             "quota": 0, "default_mailbox_quota": 0
         }
         self.ajax_post(
-            reverse('admin:domain_change', args=[self.dom.id]),
+            reverse("admin:domain_change", args=[self.dom.id]),
             values
         )
-        admin_models.DomainAlias.objects.get(name='relaydomainalias.net')
+        admin_models.DomainAlias.objects.get(name="relaydomainalias.net")
         with self.assertRaises(admin_models.DomainAlias.DoesNotExist):
-            admin_models.DomainAlias.objects.get(name='relaydomainalias.tld')
+            admin_models.DomainAlias.objects.get(name="relaydomainalias.tld")
 
     def test_delete_relaydomain(self):
         """Test the removal of a relay domain."""
@@ -308,15 +307,15 @@ class ImportTestCase(ModoTestCase):
 class LimitsTestCase(ModoTestCase, Operations):
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         """Create test data."""
         super(LimitsTestCase, cls).setUpTestData()
-        for name, tpl in limits_utils.get_user_limit_templates():
+        for name, _definition in limits_utils.get_user_limit_templates():
             cls.localconfig.parameters.set_value(
                 "deflt_user_{0}_limit".format(name), 2, app="limits")
         cls.localconfig.save()
         cls.user = UserFactory.create(
-            username='reseller', groups=('Resellers',)
+            username="reseller", groups=("Resellers",)
         )
 
     def setUp(self):
@@ -326,38 +325,38 @@ class LimitsTestCase(ModoTestCase, Operations):
 
     def test_relay_domains_limit(self):
         self._create_relay_domain(
-            'relaydomain1.tld', quota=1, default_mailbox_quota=1)
-        self._check_limit('domains', 1, 2)
+            "relaydomain1.tld", quota=1, default_mailbox_quota=1)
+        self._check_limit("domains", 1, 2)
         self._create_relay_domain(
-            'relaydomain2.tld', quota=1, default_mailbox_quota=1)
-        self._check_limit('domains', 2, 2)
-        self._create_relay_domain('relaydomain3.tld', 403)
-        self._check_limit('domains', 2, 2)
-        domid = admin_models.Domain.objects.get(name='relaydomain2.tld').id
+            "relaydomain2.tld", quota=1, default_mailbox_quota=1)
+        self._check_limit("domains", 2, 2)
+        self._create_relay_domain("relaydomain3.tld", 403)
+        self._check_limit("domains", 2, 2)
+        domid = admin_models.Domain.objects.get(name="relaydomain2.tld").id
         self.ajax_post(
-            reverse('admin:domain_delete', args=[domid]), {})
-        self._check_limit('domains', 1, 2)
+            reverse("admin:domain_delete", args=[domid]), {})
+        self._check_limit("domains", 1, 2)
 
     def test_relay_domain_aliases_limit(self):
         self._create_relay_domain(
-            'relaydomain1.tld', quota=1, default_mailbox_quota=1)
+            "relaydomain1.tld", quota=1, default_mailbox_quota=1)
         domain = admin_models.Domain.objects.get(name="relaydomain1.tld")
         self._relay_domain_alias_operation(
-            'add', domain, 'relay-domain-alias1.tld'
+            "add", domain, "relay-domain-alias1.tld"
         )
-        self._check_limit('domain_aliases', 1, 2)
+        self._check_limit("domain_aliases", 1, 2)
         self._relay_domain_alias_operation(
-            'add', domain, 'relay-domain-alias2.tld'
+            "add", domain, "relay-domain-alias2.tld"
         )
-        self._check_limit('domain_aliases', 2, 2)
+        self._check_limit("domain_aliases", 2, 2)
         self._relay_domain_alias_operation(
-            'add', domain, 'relay-domain-alias3.tld', 403
+            "add", domain, "relay-domain-alias3.tld", 403
         )
-        self._check_limit('domain_aliases', 2, 2)
+        self._check_limit("domain_aliases", 2, 2)
         self._relay_domain_alias_operation(
-            'delete', domain, 'relay-domain-alias2.tld'
+            "delete", domain, "relay-domain-alias2.tld"
         )
-        self._check_limit('domain_aliases', 1, 2)
+        self._check_limit("domain_aliases", 1, 2)
 
 
 class MapFilesTestCase(MapFilesTestCaseMixin, TestCase):
@@ -374,7 +373,7 @@ class DataMixin(object):
     """A mixin to provide test data."""
 
     @classmethod
-    def setUpTestData(cls):
+    def setUpTestData(cls):  # NOQA:N802
         super(DataMixin, cls).setUpTestData()
         transport = tr_factories.TransportFactory(
             pattern="test.com", _settings={
diff --git a/modoboa/relaydomains/transport.py b/modoboa/relaydomains/transport.py
index 8c1c77aeb..641b66897 100644
--- a/modoboa/relaydomains/transport.py
+++ b/modoboa/relaydomains/transport.py
@@ -1,5 +1,9 @@
+# -*- coding: utf-8 -*-
+
 """Transport backend definition."""
 
+from __future__ import unicode_literals
+
 from django.utils.translation import ugettext_lazy as _
 
 from modoboa.transport import backends
diff --git a/modoboa/relaydomains/urls_api.py b/modoboa/relaydomains/urls_api.py
index a7ae5cfae..56b3562b1 100644
--- a/modoboa/relaydomains/urls_api.py
+++ b/modoboa/relaydomains/urls_api.py
@@ -1,10 +1,13 @@
+# -*- coding: utf-8 -*-
+
 """Transport API urls."""
 
+from __future__ import unicode_literals
+
 from rest_framework import routers
 
 from . import viewsets
 
-
 router = routers.SimpleRouter()
 router.register(
     r"relaydomains", viewsets.RelayDomainViewSet, base_name="relaydomain")
diff --git a/modoboa/relaydomains/viewsets.py b/modoboa/relaydomains/viewsets.py
index 681f515bc..8f75e266b 100644
--- a/modoboa/relaydomains/viewsets.py
+++ b/modoboa/relaydomains/viewsets.py
@@ -1,10 +1,13 @@
+# -*- coding: utf-8 -*-
+
 """RelayDomain viewsets."""
 
+from __future__ import unicode_literals
+
 from rest_framework import viewsets
-from rest_framework.permissions import IsAuthenticated, DjangoModelPermissions
+from rest_framework.permissions import DjangoModelPermissions, IsAuthenticated
 
 from modoboa.admin import models as admin_models
-
 from . import serializers
 
 
diff --git a/modoboa/static/js/global.js b/modoboa/static/js/global.js
index a1c11a2a9..085b4c6b8 100644
--- a/modoboa/static/js/global.js
+++ b/modoboa/static/js/global.js
@@ -136,6 +136,7 @@ function display_form_errors(formid, data) {
         var $widget = $("#" + formid + " #" + fullid);
         var spanid = fullid + "-error";
         var $span = $("#" + spanid);
+        var error = value.join(' ');
 
         if (!$widget.parents(".form-group").hasClass("has-error")) {
             $widget.parents(".form-group").addClass("has-error");
@@ -143,12 +144,12 @@ function display_form_errors(formid, data) {
         if (!$span.length) {
             $span = $("<span />", {
                 "class": "help-block",
-                "html": value[0],
+                "html": error,
                 "id": spanid
             });
             $widget.parents(".form-group").append($span);
         } else {
-            $span.html(value[0]);
+            $span.html(error);
         }
     });
 }
diff --git a/modoboa/static/js/twocols_nav.js b/modoboa/static/js/twocols_nav.js
index 3401e0933..0903276b0 100644
--- a/modoboa/static/js/twocols_nav.js
+++ b/modoboa/static/js/twocols_nav.js
@@ -36,13 +36,15 @@ TwocolsNav.prototype = {
                 success_cb: $.proxy(this.save_cb, this)
             });
         }, this));
-        $(document).on('submit', '#parameters_form', $.proxy(function(evt) {
+        var formId = 'parameters_form';
+        $(document).on('submit', '#' + formId, $.proxy(function(evt) {
             simple_ajax_form_post(evt, {
-                formid: $(this).attr('id'),
+                formid: formId,
                 modal: false,
                 reload_on_success: false,
                 success_cb: $.proxy(this.save_cb, this),
                 error_cb: function(data) {
+                    window.scrollTo(0, 0);
                     $('a[data-app="' + data.prefix + '"]').tab('show');
                 }
             });
diff --git a/modoboa/test_settings.py b/modoboa/test_settings.py
index 69738187b..535b8c3c1 100644
--- a/modoboa/test_settings.py
+++ b/modoboa/test_settings.py
@@ -7,46 +7,61 @@ import os
 # Database
 # https://docs.djangoproject.com/en/1.11/ref/settings/#databases
 
-DB = os.environ.get('DB', 'POSTGRESQL')
+DB = os.environ.get("DB", "POSTGRESQL")
 
-if DB == 'MYSQL':
+if DB == "MYSQL":
     DATABASES = {
-        'default': {
-            'ENGINE': 'django.db.backends.mysql',
-            'NAME': 'modoboa',
-            'USER': 'root',
-            'PASSWORD': '',
-            'HOST': 'localhost',
-            'PORT': '',
-            'ATOMIC_REQUESTS': True,
+        "default": {
+            "ENGINE": "django.db.backends.mysql",
+            "NAME": "modoboa",
+            "USER": "root",
+            "PASSWORD": "",
+            "HOST": "localhost",
+            "PORT": "",
+            "ATOMIC_REQUESTS": True,
             # MySQL's Strict Mode fixes many data integrity problems in MySQL,
             # such as data truncation upon insertion, by escalating warnings
             # into errors. It is strongly recommended you activate it.
             # MySQL >= 5.7 set STRICT_TRANS_TABLES by default
-            # See: https://docs.djangoproject.com/en/1.11/ref/databases/#mysql-sql-mode
-            'OPTIONS': {
-                'init_command': 'SET sql_mode=\'STRICT_TRANS_TABLES\'',
+            # See:
+            # https://docs.djangoproject.com/en/1.11/ref/databases/#mysql-sql-mode
+            "OPTIONS": {
+                "init_command": (
+                    "SET sql_mode = 'STRICT_TRANS_TABLES';"
+                    "SET innodb_strict_mode = ON;"
+                ),
+                "charset": "utf8",
+            },
+            "TEST": {
+                "CHARSET": "utf8",
+                "COLLATION": "utf8_unicode_ci",
             },
         },
     }
-elif DB == 'SQLITE':
+elif DB == "SQLITE":
     DATABASES = {
-        'default': {
-            'ENGINE': 'django.db.backends.sqlite3',
-            'NAME': 'modoboa.db',
-            'PORT': '',
-            'ATOMIC_REQUESTS': True,
+        "default": {
+            "ENGINE": "django.db.backends.sqlite3",
+            "NAME": "modoboa.db",
+            "PORT": "",
+            "ATOMIC_REQUESTS": True,
         },
     }
 else:
     DATABASES = {
-        'default': {
-            'ENGINE': 'django.db.backends.postgresql',
-            'NAME': 'modoboa',
-            'USER': 'postgres',
-            'PASSWORD': '',
-            'HOST': 'localhost',
-            'PORT': '',
-            'ATOMIC_REQUESTS': True,
+        "default": {
+            "ENGINE": "django.db.backends.postgresql",
+            "NAME": "modoboa",
+            "USER": "postgres",
+            "PASSWORD": "",
+            "HOST": "localhost",
+            "PORT": "",
+            "ATOMIC_REQUESTS": True,
+            "OPTIONS": {
+                    "client_encoding": "UTF8",
+            },
+            "TEST": {
+                "CHARSET": "UTF8",
+            },
         },
     }
diff --git a/modoboa/transport/__init__.py b/modoboa/transport/__init__.py
index ba19ffc3c..96b626725 100644
--- a/modoboa/transport/__init__.py
+++ b/modoboa/transport/__init__.py
@@ -1 +1,5 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import unicode_literals
+
 default_app_config = "modoboa.transport.apps.TransportConfig"
diff --git a/modoboa/transport/apps.py b/modoboa/transport/apps.py
index 7162f121b..7d27b0001 100644
--- a/modoboa/transport/apps.py
+++ b/modoboa/transport/apps.py
@@ -1,11 +1,12 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from django.apps import AppConfig
 
 
 class TransportConfig(AppConfig):
-    name = 'modoboa.transport'
+    name = "modoboa.transport"
 
     def ready(self):
-        from . import handlers
-        
+        from . import handlers  # NOQA:F401
diff --git a/modoboa/transport/backends.py b/modoboa/transport/backends.py
index 53e5e2789..dc2ae5500 100644
--- a/modoboa/transport/backends.py
+++ b/modoboa/transport/backends.py
@@ -1,5 +1,9 @@
+# -*- coding: utf-8 -*-
+
 """Transport backend."""
 
+from __future__ import unicode_literals
+
 from django import forms
 from django.core import validators
 from django.utils.translation import ugettext_lazy as _
@@ -76,10 +80,13 @@ class TransportBackendManager(object):
 
     def get_backend_list(self):
         """Return known backend list."""
-        return sorted([
-            (key, key)
-            for key, backend in self.backends.items()
-        ], key=lambda i: i[1])
+        return sorted(
+            (
+                (key, key)
+                for key, backend in self.backends.items()
+            ),
+            key=lambda i: i[1]
+        )
 
     def get_backend_settings(self, name):
         """Return backend settings."""
diff --git a/modoboa/transport/constants.py b/modoboa/transport/constants.py
index 80c50d66b..b1786c081 100644
--- a/modoboa/transport/constants.py
+++ b/modoboa/transport/constants.py
@@ -1,5 +1,9 @@
+# -*- coding: utf-8 -*-
+
 """Transport constants."""
 
+from __future__ import unicode_literals
+
 PERMISSIONS = {
 
 }
diff --git a/modoboa/transport/factories.py b/modoboa/transport/factories.py
index 332bd400a..7e08e0b34 100644
--- a/modoboa/transport/factories.py
+++ b/modoboa/transport/factories.py
@@ -1,5 +1,9 @@
+# -*- coding: utf-8 -*-
+
 """Transport factories."""
 
+from __future__ import unicode_literals
+
 import factory
 
 from . import models
diff --git a/modoboa/transport/forms.py b/modoboa/transport/forms.py
index df46b5a56..9309e0413 100644
--- a/modoboa/transport/forms.py
+++ b/modoboa/transport/forms.py
@@ -1,10 +1,12 @@
+# -*- coding: utf-8 -*-
+
 """Transport forms."""
 
+from __future__ import unicode_literals
+
 from django import forms
 
-from . import backends
-from . import models
-
+from . import backends, models
 
 TYPE_TO_FIELD_MAP = {
     "int": forms.IntegerField,
diff --git a/modoboa/transport/handlers.py b/modoboa/transport/handlers.py
index 1e69bf921..427a420c2 100644
--- a/modoboa/transport/handlers.py
+++ b/modoboa/transport/handlers.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Transport handlers."""
 
 from __future__ import unicode_literals
@@ -6,10 +8,7 @@ from django.db.models import signals
 from django.dispatch import receiver
 
 from modoboa.core import signals as core_signals
-
-from . import backends
-from . import models
-from . import postfix_maps
+from . import backends, models, postfix_maps
 
 
 @receiver(core_signals.register_postfix_maps)
diff --git a/modoboa/transport/models.py b/modoboa/transport/models.py
index e8b011008..b37991f85 100644
--- a/modoboa/transport/models.py
+++ b/modoboa/transport/models.py
@@ -1,14 +1,15 @@
+# -*- coding: utf-8 -*-
+
 """Transport models."""
 
 from __future__ import unicode_literals
 
+import jsonfield
 from reversion import revisions as reversion
 
 from django.db import models
 from django.utils.translation import ugettext_lazy as _
 
-import jsonfield
-
 from . import backends
 
 
diff --git a/modoboa/transport/postfix_maps.py b/modoboa/transport/postfix_maps.py
index be5aa51c9..a756fd57d 100644
--- a/modoboa/transport/postfix_maps.py
+++ b/modoboa/transport/postfix_maps.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """Map file definitions for postfix."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/transport/static/transport/js/transport.js b/modoboa/transport/static/transport/js/transport.js
index c6b1a695a..e0097342e 100644
--- a/modoboa/transport/static/transport/js/transport.js
+++ b/modoboa/transport/static/transport/js/transport.js
@@ -21,5 +21,6 @@ function transportFormCallback () {
 }
 
 $(document).ready(function () {
+    $(this).bind('domwizard_init', transportFormCallback);
     $(this).bind('domform_init', transportFormCallback);
 });
diff --git a/modoboa/urls.py b/modoboa/urls.py
index 92584b7ba..650816886 100644
--- a/modoboa/urls.py
+++ b/modoboa/urls.py
@@ -1,33 +1,34 @@
+# -*- coding: utf-8 -*-
+
 from __future__ import unicode_literals
 
 from functools import reduce
 
+from ckeditor_uploader import views as cku_views
+
 from django.conf import settings
 from django.conf.urls import include, url
-from django.views.i18n import JavaScriptCatalog
-
 from django.contrib.auth import views as auth_views
 from django.contrib.auth.decorators import login_required
+from django.views.i18n import JavaScriptCatalog
 
-from ckeditor_uploader import views as cku_views
 from rest_framework.documentation import include_docs_urls
 
 from modoboa.admin.views.user import forward
-from modoboa.core import signals as core_signals
-from modoboa.core import views as core_views
+from modoboa.core import signals as core_signals, views as core_views
 from modoboa.core.extensions import exts_pool
 
-API_TITLE = 'Modoboa API'
+API_TITLE = "Modoboa API"
 
 urlpatterns = [
-    url(r'^jsi18n/$', JavaScriptCatalog.as_view(), name='javascript-catalog'),
+    url(r'^jsi18n/$', JavaScriptCatalog.as_view(), name="javascript-catalog"),
     url(r'^ckeditor/upload/', login_required(cku_views.upload),
         name="ckeditor_upload"),
     url(r'^ckeditor/browse/', login_required(cku_views.browse),
         name="ckeditor_browse"),
-    url('', include('modoboa.core.urls', namespace="core")),
-    url('^user/forward/', forward, name="user_forward"),
-    url('admin/', include('modoboa.admin.urls', namespace="admin")),
+    url("", include("modoboa.core.urls", namespace="core")),
+    url("^user/forward/", forward, name="user_forward"),
+    url("admin/", include("modoboa.admin.urls", namespace="admin")),
     # No namespace
     url(r'^accounts/password_reset/$', core_views.password_reset,
         name="password_reset"),
diff --git a/modoboa/urls_api.py b/modoboa/urls_api.py
index 43ce98a83..ea1770cda 100644
--- a/modoboa/urls_api.py
+++ b/modoboa/urls_api.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 """External API urls."""
 
 from __future__ import unicode_literals
@@ -6,7 +8,6 @@ from django.conf.urls import include, url
 
 from modoboa.core.extensions import exts_pool
 
-
 urlpatterns = [
     url("", include("modoboa.admin.urls_api")),
     url("", include("modoboa.limits.urls_api")),
diff --git a/postgresql-requirements.txt b/postgresql-requirements.txt
index 59041b90e..a50ac6574 100644
--- a/postgresql-requirements.txt
+++ b/postgresql-requirements.txt
@@ -1 +1 @@
-psycopg2>=2.5.4
+psycopg2-binary>=2.7.4
diff --git a/requirements.txt b/requirements.txt
index 502067794..20965afed 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,13 +11,12 @@ coreapi==2.3.3
 coreapi-cli==1.0.6
 djangorestframework==3.7.3
 
-argparse
 # bcrypt requires libffi-dev
 bcrypt==3.1.4
 dnspython==1.15.0
 feedparser==5.2.1
 gevent==1.2.2
-ipaddress
+ipaddress; python_version < '3.3'
 jsonfield==2.0.2
 passlib==1.7.1
 progressbar33==2.4
@@ -27,5 +26,5 @@ pytz
 requests
 rfc6266
 lxml
-backports.csv
+backports.csv; python_version < '3'
 chardet
diff --git a/setup.cfg b/setup.cfg
index 66d21b5cc..6f8d0cca9 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,26 @@
 [bdist_wheel]
 universal = 1
+
+[isort]
+atomic = true
+combine_as_imports = true
+combine_star = true
+default_section = THIRDPARTY
+indent = '    '
+known_django = django
+known_drf = rest_framework
+known_first_party = modoboa,test_project
+multi_line_output = 5
+no_lines_before = LOCALFOLDER
+not_skip = __init__.py
+sections = FUTURE,STDLIB,THIRDPARTY,DJANGO,DRF,FIRSTPARTY,LOCALFOLDER
+skip_glob = **/migrations/*.py
+use_parentheses = true
+
 [pep8]
-max-line-length = 80
 exclude = migrations
+max-line-length = 80
+
+[flake8]
+exclude = migrations
+max-line-length = 80
diff --git a/setup.py b/setup.py
index 5d4e2db31..a9984a9db 100644
--- a/setup.py
+++ b/setup.py
@@ -12,8 +12,14 @@ from __future__ import unicode_literals
 
 import io
 from os import path
-from pip.req import parse_requirements
-from setuptools import setup, find_packages
+
+try:
+    from pip.req import parse_requirements
+except ImportError:
+    # pip >= 10
+    from pip._internal.req import parse_requirements
+
+from setuptools import find_packages, setup
 
 
 def get_requirements(requirements_file):
@@ -21,12 +27,10 @@ def get_requirements(requirements_file):
     requirements = []
     if path.isfile(requirements_file):
         for req in parse_requirements(requirements_file, session="hack"):
-            # check markers, such as
-            #
-            #     rope_py3k    ; python_version >= '3.0'
-            #
-            if req.match_markers():
-                requirements.append(str(req.req))
+            if req.markers:
+                requirements.append("%s;%s" % (req.req, req.markers))
+            else:
+                requirements.append("%s" % req.req)
     return requirements
 
 
diff --git a/test-requirements.txt b/test-requirements.txt
index fa89fafc7..00fae81e6 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,7 +1,5 @@
 factory-boy>=2.4
-mock==2.0.0
+mock==2.0.0; python_version < '3.3'
 httmock==1.2.5
 testfixtures==4.7.0
 tox
-psycopg2>=2.5.4
-mysqlclient>=1.3.3
diff --git a/test_project/test_project/settings.py b/test_project/test_project/settings.py
index ca0df91f2..9b5f0e166 100644
--- a/test_project/test_project/settings.py
+++ b/test_project/test_project/settings.py
@@ -12,12 +12,11 @@ https://docs.djangoproject.com/en/1.11/ref/settings/
 
 from __future__ import unicode_literals
 
-from logging.handlers import SysLogHandler
 import os
+from logging.handlers import SysLogHandler
 
 from modoboa.test_settings import *  # noqa
 
-
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
 BASE_DIR = os.path.realpath(os.path.dirname(os.path.dirname(__file__)))
 
@@ -26,16 +25,16 @@ BASE_DIR = os.path.realpath(os.path.dirname(os.path.dirname(__file__)))
 # See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/
 
 # SECURITY WARNING: keep the secret key used in production secret!
-SECRET_KEY = '!8o(-dbbl3e+*bh7nx-^xysdt)1gso*%@4ze4-9_9o+i&amp;t--u_'
+SECRET_KEY = "!8o(-dbbl3e+*bh7nx-^xysdt)1gso*%@4ze4-9_9o+i&amp;t--u_"
 
 # SECURITY WARNING: don't run with debug turned on in production!
-DEBUG = 'DEBUG' in os.environ
+DEBUG = "DEBUG" in os.environ
 
 TEMPLATE_DEBUG = DEBUG
 
 ALLOWED_HOSTS = [
-    '127.0.0.1',
-    'localhost',
+    "127.0.0.1",
+    "localhost",
 ]
 
 SITE_ID = 1
@@ -47,57 +46,57 @@ X_FRAME_OPTIONS = "SAMEORIGIN"
 # Application definition
 
 INSTALLED_APPS = (
-    'django.contrib.auth',
-    'django.contrib.contenttypes',
-    'django.contrib.sessions',
-    'django.contrib.messages',
-    'django.contrib.sites',
-    'django.contrib.staticfiles',
-    'reversion',
-    'ckeditor',
-    'ckeditor_uploader',
-    'rest_framework',
-    'rest_framework.authtoken',
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "django.contrib.messages",
+    "django.contrib.sites",
+    "django.contrib.staticfiles",
+    "reversion",
+    "ckeditor",
+    "ckeditor_uploader",
+    "rest_framework",
+    "rest_framework.authtoken",
 )
 
 # A dedicated place to register Modoboa applications
 # Do not delete it.
 # Do not change the order.
 MODOBOA_APPS = (
-    'modoboa',
-    'modoboa.core',
-    'modoboa.lib',
-    'modoboa.admin',
-    'modoboa.transport',
-    'modoboa.relaydomains',
-    'modoboa.limits',
-    'modoboa.parameters',
+    "modoboa",
+    "modoboa.core",
+    "modoboa.lib",
+    "modoboa.admin",
+    "modoboa.transport",
+    "modoboa.relaydomains",
+    "modoboa.limits",
+    "modoboa.parameters",
     # Modoboa extensions here.
 )
 
 INSTALLED_APPS += MODOBOA_APPS
 
-AUTH_USER_MODEL = 'core.User'
+AUTH_USER_MODEL = "core.User"
 
 MIDDLEWARE = (
-    'x_forwarded_for.middleware.XForwardedForMiddleware',
-    'django.contrib.sessions.middleware.SessionMiddleware',
-    'django.middleware.common.CommonMiddleware',
-    'django.middleware.csrf.CsrfViewMiddleware',
-    'django.contrib.auth.middleware.AuthenticationMiddleware',
-    'django.contrib.messages.middleware.MessageMiddleware',
-    'django.middleware.locale.LocaleMiddleware',
-    'django.middleware.clickjacking.XFrameOptionsMiddleware',
-    'modoboa.core.middleware.LocalConfigMiddleware',
-    'modoboa.lib.middleware.AjaxLoginRedirect',
-    'modoboa.lib.middleware.CommonExceptionCatcher',
-    'modoboa.lib.middleware.RequestCatcherMiddleware',
+    "x_forwarded_for.middleware.XForwardedForMiddleware",
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.common.CommonMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "django.contrib.messages.middleware.MessageMiddleware",
+    "django.middleware.locale.LocaleMiddleware",
+    "django.middleware.clickjacking.XFrameOptionsMiddleware",
+    "modoboa.core.middleware.LocalConfigMiddleware",
+    "modoboa.lib.middleware.AjaxLoginRedirect",
+    "modoboa.lib.middleware.CommonExceptionCatcher",
+    "modoboa.lib.middleware.RequestCatcherMiddleware",
 )
 
 AUTHENTICATION_BACKENDS = (
     # 'modoboa.lib.authbackends.LDAPBackend',
     # 'modoboa.lib.authbackends.SMTPBackend',
-    'django.contrib.auth.backends.ModelBackend',
+    "django.contrib.auth.backends.ModelBackend",
 )
 
 # SMTP authentication
@@ -108,37 +107,37 @@ AUTHENTICATION_BACKENDS = (
 
 TEMPLATES = [
     {
-        'BACKEND': 'django.template.backends.django.DjangoTemplates',
-        'DIRS': [],
-        'APP_DIRS': True,
-        'OPTIONS': {
-            'context_processors': [
-                'django.template.context_processors.debug',
-                'django.template.context_processors.request',
-                'django.contrib.auth.context_processors.auth',
-                'django.template.context_processors.i18n',
-                'django.template.context_processors.media',
-                'django.template.context_processors.static',
-                'django.template.context_processors.tz',
-                'django.contrib.messages.context_processors.messages',
-                'modoboa.core.context_processors.top_notifications',
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "APP_DIRS": True,
+        "OPTIONS": {
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.template.context_processors.i18n",
+                "django.template.context_processors.media",
+                "django.template.context_processors.static",
+                "django.template.context_processors.tz",
+                "django.contrib.messages.context_processors.messages",
+                "modoboa.core.context_processors.top_notifications",
             ],
-            'debug': TEMPLATE_DEBUG,
+            "debug": TEMPLATE_DEBUG,
         },
     },
 ]
 
-ROOT_URLCONF = 'test_project.urls'
+ROOT_URLCONF = "test_project.urls"
 
-WSGI_APPLICATION = 'test_project.wsgi.application'
+WSGI_APPLICATION = "test_project.wsgi.application"
 
 
 # Internationalization
 # https://docs.djangoproject.com/en/1.11/topics/i18n/
 
-LANGUAGE_CODE = 'en-us'
+LANGUAGE_CODE = "en-us"
 
-TIME_ZONE = 'UTC'
+TIME_ZONE = "UTC"
 
 USE_I18N = True
 
@@ -149,21 +148,21 @@ USE_TZ = True
 # Static files (CSS, JavaScript, Images)
 # https://docs.djangoproject.com/en/1.11/howto/static-files/
 
-STATIC_URL = '/sitestatic/'
-STATIC_ROOT = os.path.join(BASE_DIR, 'sitestatic')
+STATIC_URL = "/sitestatic/"
+STATIC_ROOT = os.path.join(BASE_DIR, "sitestatic")
 STATICFILES_DIRS = (
-    os.path.join(BASE_DIR, '..', 'modoboa', 'bower_components'),
+    os.path.join(BASE_DIR, "..", "modoboa", "bower_components"),
 )
 
-MEDIA_URL = '/media/'
-MEDIA_ROOT = os.path.join(BASE_DIR, 'media')
+MEDIA_URL = "/media/"
+MEDIA_ROOT = os.path.join(BASE_DIR, "media")
 
 # Rest framework settings
 
 REST_FRAMEWORK = {
-    'DEFAULT_AUTHENTICATION_CLASSES': (
-        'rest_framework.authentication.TokenAuthentication',
-        'rest_framework.authentication.SessionAuthentication',
+    "DEFAULT_AUTHENTICATION_CLASSES": (
+        "rest_framework.authentication.TokenAuthentication",
+        "rest_framework.authentication.SessionAuthentication",
     ),
 }
 
@@ -172,31 +171,31 @@ REST_FRAMEWORK = {
 
 # DOVECOT_LOOKUP_PATH = ('/path/to/dovecot', )
 
-MODOBOA_API_URL = 'https://api.modoboa.org/1/'
+MODOBOA_API_URL = "https://api.modoboa.org/1/"
 
 # Password validation
 # https://docs.djangoproject.com/en/1.11/ref/settings/#auth-password-validators
 
 AUTH_PASSWORD_VALIDATORS = [
     {
-        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
+        "NAME": "django.contrib.auth.password_validation.UserAttributeSimilarityValidator",  # NOQA:E501
     },
     {
-        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
+        "NAME": "django.contrib.auth.password_validation.MinimumLengthValidator",  # NOQA:E501
     },
     {
-        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
+        "NAME": "django.contrib.auth.password_validation.CommonPasswordValidator",  # NOQA:E501
     },
     {
-        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
+        "NAME": "django.contrib.auth.password_validation.NumericPasswordValidator",  # NOQA:E501
     },
     {
-        'NAME': 'modoboa.core.password_validation.ComplexityValidator',
-        'OPTIONS': {
-            'upper': 1,
-            'lower': 1,
-            'digits': 1,
-            'specials': 0
+        "NAME": "modoboa.core.password_validation.ComplexityValidator",
+        "OPTIONS": {
+            "upper": 1,
+            "lower": 1,
+            "digits": 1,
+            "specials": 0
         }
     },
 ]
@@ -214,21 +213,21 @@ CKEDITOR_BROWSE_SHOW_DIRS = True
 CKEDITOR_ALLOW_NONIMAGE_FILES = False
 
 CKEDITOR_CONFIGS = {
-    'default': {
-        'allowedContent': True,
-        'toolbar': 'Modoboa',
-        'width': None,
-        'toolbar_Modoboa': [
-            ['Bold', 'Italic', 'Underline'],
-            ['JustifyLeft', 'JustifyCenter', 'JustifyRight', 'JustifyBlock'],
-            ['BidiLtr', 'BidiRtl', 'Language'],
-            ['NumberedList', 'BulletedList', '-', 'Outdent', 'Indent'],
-            ['Undo', 'Redo'],
-            ['Link', 'Unlink', 'Anchor', '-', 'Smiley'],
-            ['TextColor', 'BGColor', '-', 'Source'],
-            ['Font', 'FontSize'],
-            ['Image', ],
-            ['SpellChecker']
+    "default": {
+        "allowedContent": True,
+        "toolbar": "Modoboa",
+        "width": None,
+        "toolbar_Modoboa": [
+            ["Bold", "Italic", "Underline"],
+            ["JustifyLeft", "JustifyCenter", "JustifyRight", "JustifyBlock"],
+            ["BidiLtr", "BidiRtl", "Language"],
+            ["NumberedList", "BulletedList", "-", "Outdent", "Indent"],
+            ["Undo", "Redo"],
+            ["Link", "Unlink", "Anchor", "-", "Smiley"],
+            ["TextColor", "BGColor", "-", "Source"],
+            ["Font", "FontSize"],
+            ["Image", ],
+            ["SpellChecker"]
         ],
     },
 }
@@ -236,33 +235,33 @@ CKEDITOR_CONFIGS = {
 # Logging configuration
 
 LOGGING = {
-    'version': 1,
-    'disable_existing_loggers': False,
-    'formatters': {
-        'syslog': {
-            'format': '%(name)s: %(levelname)s %(message)s'
+    "version": 1,
+    "disable_existing_loggers": False,
+    "formatters": {
+        "syslog": {
+            "format": "%(name)s: %(levelname)s %(message)s"
         },
     },
-    'handlers': {
-        'syslog-auth': {
-            'class': 'logging.handlers.SysLogHandler',
-            'facility': SysLogHandler.LOG_AUTH,
-            'formatter': 'syslog'
+    "handlers": {
+        "syslog-auth": {
+            "class": "logging.handlers.SysLogHandler",
+            "facility": SysLogHandler.LOG_AUTH,
+            "formatter": "syslog"
         },
-        'modoboa': {
-            'class': 'modoboa.core.loggers.SQLHandler',
+        "modoboa": {
+            "class": "modoboa.core.loggers.SQLHandler",
         }
     },
-    'loggers': {
-        'modoboa.auth': {
-            'handlers': ['syslog-auth', 'modoboa'],
-            'level': 'INFO',
-            'propagate': False
+    "loggers": {
+        "modoboa.auth": {
+            "handlers": ["syslog-auth", "modoboa"],
+            "level": "INFO",
+            "propagate": False
         },
-        'modoboa.admin': {
-            'handlers': ['modoboa'],
-            'level': 'INFO',
-            'propagate': False
+        "modoboa.admin": {
+            "handlers": ["modoboa"],
+            "level": "INFO",
+            "propagate": False
         }
     }
 }
diff --git a/tests.py b/tests.py
index 69a5e184f..5177a3ec3 100644
--- a/tests.py
+++ b/tests.py
@@ -1,4 +1,6 @@
 # coding: utf-8
+from __future__ import unicode_literals
+
 import os
 import tempfile
 import unittest
@@ -25,7 +27,7 @@ class DeployTest(unittest.TestCase):
         cmd = (
             "modoboa-admin.py deploy --collectstatic "
             "--dburl %s --domain %s --admin-username admin %s"
-            % (dburl, 'localhost', self.projname)
+            % (dburl, "localhost", self.projname)
         )
         code, output = exec_cmd(cmd, cwd=self.workdir)
         self.assertEqual(code, 0)
diff --git a/tox.ini b/tox.ini
index 1f949ddfd..9f3dd8fc9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,8 +9,11 @@ commands =
 
     coverage report --show-missing
 deps =
+    -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
     coverage
+    postgres: -r{toxinidir}/postgresql-requirements.txt
+    mysql: -r{toxinidir}/mysql-requirements.txt
 setenv =
     COVERAGE_FILE={envdir}/.coverage
     DB=SQLITE