Make sure to catch all DNS exceptions.

doc/manual_installation/dovecot.rst

@@ -254,6 +254,8 @@ For debian and derivative, you need to install sqlite connector for dovecot::
 
    Replace values between ``<>`` with yours.
 
+.. _dovecot_oauth2:
+
 OAuth 2 authentication
 ======================
 
@@ -264,9 +266,7 @@ application with the following commands:
 .. sourcecode:: bash
 
    > cd <modoboa_instance_path>
-   > python manage.py createapplication --name=Dovecot --algorithm=RS256 --skip-authorization --redirect-uris=http://localhost --client-secret=<client_secret> public authorization-code
-
-Choose a value for ``<client_secret>`` (you can generate a random one).
+   > python manage.py createapplication --name=Dovecot --skip-authorization --client-id=dovecot confidential client-credentials
 
 On success, you should see an output similar to::
 
@@ -291,13 +291,13 @@ Finally, create a file named :file:`conf.d/dovecot-oauth2.conf.ext` with the
 following content::
 
   introspection_mode = post
-  introspection_url = http://<client_id>:<client_secret>@localhost/api/o/introspect/
+  introspection_url = http://dovecot:<client_secret>@localhost/api/o/introspect/
   username_attribute = username
   tls_ca_cert_file = /etc/ssl/certs/ca-certificates.crt
   active_attribute = active
   active_value = true
 
-Replace ``<client_id>`` and ``<client_secret>`` with the values you obtained earlier.
+Replace ``<client_secret>`` with the value you obtained earlier.
 
 LDAP
 ====

doc/upgrade.rst

@@ -331,6 +331,12 @@ by default.
       # If CORS fail, you might want to try to set it to True
       #CORS_ORIGIN_ALLOW_ALL = False
 
+Docevot configuration changes
+-----------------------------
+
+You must enable oauth2 authentication in Dovecot to make the filters
+editor work in the new UI. Follow this :ref:`guide <dovecot_oauth2>`.
+
 Post update
 -----------
 

modoboa/admin/lib.py

@@ -192,13 +192,13 @@ def get_dns_resolver():
 
 def get_authoritative_server(domain, resolver=None):
     if not resolver:
-       resolver = get_dns_resolver()
+        resolver = get_dns_resolver()
 
     dnsname = dns.name.from_text(domain)
 
     while True:
         try:
-            answers = dns.resolver.resolve(dnsname, 'NS')
+            answers = dns.resolver.resolve(dnsname, "NS")
             if answers:
                 first_answer = answers[0]
                 if hasattr(first_answer, "target"):
@@ -214,7 +214,7 @@ def get_authoritative_server(domain, resolver=None):
 def get_authoritative_ip(domain, resolver=None):
     dnsserver_name = get_authoritative_server(domain, resolver=resolver)
     if not resolver:
-       resolver = get_dns_resolver()
+        resolver = get_dns_resolver()
     answer = resolver.resolve(dnsserver_name)
     if answer:
         return answer[0].address
@@ -235,8 +235,8 @@ def get_dns_records(name, typ, resolver=None):
     """Retrieve DNS records for given name and type."""
     logger = logging.getLogger("modoboa.admin")
 
-    resolver = get_authoritative_resolver(name, resolver=resolver)
     try:
+        resolver = get_authoritative_resolver(name, resolver=resolver)
         dns_answers = resolver.resolve(name, typ, search=True)
     except dns.resolver.NXDOMAIN as e:
         logger.error(_("No DNS record found for %s") % name, exc_info=e)