diff --git a/modoboa/core/app_settings.py b/modoboa/core/app_settings.py
index 7b4aaeee1..656b0ffbd 100644
--- a/modoboa/core/app_settings.py
+++ b/modoboa/core/app_settings.py
@@ -462,7 +462,7 @@ class GeneralParametersForm(param_forms.AdminParametersForm):
         initial=30,
         help_text=_(
             "An account with a last login date greater than this threshold "
-            "(in days) will be considered as inactive"
+            "(in days) will be considered as inactive. Disabled if the number is negative."
         ),
     )
 
@@ -1076,7 +1076,8 @@ GLOBAL_PARAMETERS_STRUCT = collections.OrderedDict([
                 "label": ugettext_lazy("Inactive account threshold"),
                 "help_text": ugettext_lazy(
                     "An account with a last login date greater than this "
-                    "threshold (in days) will be considered as inactive"
+                    "threshold (in days) will be considered as inactive. "
+                    "Disabled if the number is negative."
                 )
             }),
             ("top_notifications_check_interval", {
diff --git a/modoboa/core/management/commands/clean_inactive_accounts.py b/modoboa/core/management/commands/clean_inactive_accounts.py
index eb5e58778..23cd06e3a 100644
--- a/modoboa/core/management/commands/clean_inactive_accounts.py
+++ b/modoboa/core/management/commands/clean_inactive_accounts.py
@@ -45,6 +45,8 @@ class Command(BaseCommand):
         """Command entry point."""
         inactive_account_threshold = param_tools.get_global_parameter(
             "inactive_account_threshold")
+        if inactive_account_threshold < 0:
+            return
         qset = models.User.objects.filter(
             is_active=True, is_superuser=False,
             last_login__lt=timezone.now() -
diff --git a/modoboa/core/tests/test_core.py b/modoboa/core/tests/test_core.py
index b0b476bc2..a738918d5 100644
--- a/modoboa/core/tests/test_core.py
+++ b/modoboa/core/tests/test_core.py
@@ -11,7 +11,7 @@ from django.test import TestCase
 from django.urls import reverse
 from django.utils import timezone
 
-from modoboa.lib.tests import ModoTestCase
+from modoboa.lib.tests import ModoTestCase, SimpleModoTestCase
 from .. import factories, mocks, models
 
 
@@ -44,7 +44,7 @@ class AuthenticationTestCase(ModoTestCase):
         self.assertTrue(response.url.endswith(reverse("core:dashboard")))
 
 
-class ManagementCommandsTestCase(TestCase):
+class ManagementCommandsTestCase(SimpleModoTestCase):
     """Test management commands."""
 
     def test_change_default_admin(self):
@@ -84,6 +84,14 @@ class ManagementCommandsTestCase(TestCase):
             "clean_inactive_accounts", "--verbose", "--dry-run", stdout=out)
         self.assertIn("user1@domain.test", out.getvalue())
 
+        # Set a negative number (means disabled)
+        self.set_global_parameter("inactive_account_threshold", -1)
+        out = StringIO()
+        management.call_command(
+            "clean_inactive_accounts", "--verbose", "--dry-run", stdout=out)
+        self.assertEqual("", out.getvalue())
+
+        self.set_global_parameter("inactive_account_threshold", 30)
         management.call_command("clean_inactive_accounts", "--silent")
         account.refresh_from_db()
         self.assertFalse(account.is_active)
diff --git a/modoboa/lib/tests/__init__.py b/modoboa/lib/tests/__init__.py
index 608197a41..06cc1862f 100644
--- a/modoboa/lib/tests/__init__.py
+++ b/modoboa/lib/tests/__init__.py
@@ -51,6 +51,9 @@ class ParametersMixin(object):
         self.localconfig.parameters.set_values(parameters, app=app)
         self.localconfig.save()
 
+class SimpleModoTestCase(ParametersMixin, TestCase):
+    """Simple class to add parameters editing."""
+
 
 class ModoTestCase(ParametersMixin, TestCase):
     """All test cases must inherit from this one."""