diff --git a/modoboa/core/tests/test_authentication.py b/modoboa/core/tests/test_authentication.py
index e3e9a47d0..9e8e91230 100644
--- a/modoboa/core/tests/test_authentication.py
+++ b/modoboa/core/tests/test_authentication.py
@@ -4,12 +4,14 @@ from __future__ import unicode_literals
 
 import smtplib
 
+from unittest import skipIf
 from mock import patch
 
 from django.core.urlresolvers import reverse
 from django.test import override_settings
 
 from modoboa.lib.tests import ModoTestCase
+from modoboa.lib.tests import NO_SMTP
 
 from .. import factories
 from .. import models
@@ -43,6 +45,7 @@ class AuthenticationTestCase(ModoTestCase):
         self.assertTrue(response.url.endswith(reverse("core:dashboard")))
 
 
+@skipIf(NO_SMTP, 'No SMTP server available')
 @override_settings(AUTHENTICATION_BACKENDS=(
     "modoboa.lib.authbackends.SMTPBackend",
     "django.contrib.auth.backends.ModelBackend"
diff --git a/modoboa/lib/tests.py b/modoboa/lib/tests.py
index e86d6a405..3fbab598a 100644
--- a/modoboa/lib/tests.py
+++ b/modoboa/lib/tests.py
@@ -3,6 +3,8 @@
 
 from __future__ import unicode_literals
 
+import socket
+
 from django.core import management
 from django.test import TestCase
 
@@ -13,6 +15,13 @@ from modoboa.core import models as core_models
 
 from . import sysutils
 
+try:
+    s = socket.create_connection(('127.0.0.1', 25))
+    s.close()
+    NO_SMTP = False
+except socket.error:
+    NO_SMTP = True
+
 try:
     import ldap  # NOQA
     NO_LDAP = False