This event can raise a list of alias too...

see #693

modoboa/extensions/amavis/general_callbacks.py

@@ -103,12 +103,14 @@ def on_mailboxalias_created(user, alias):
 
 
 @events.observe("MailboxAliasDeleted")
-def on_mailboxalias_deleted(alias):
+def on_mailboxalias_deleted(aliases):
     """Clean amavis database when an alias is removed."""
     if parameters.get_admin("MANUAL_LEARNING") == "no":
         return
-    if Users.objects.filter(email=alias.full_address).exists():
-        Users.objects.delete(email=alias.full_address)
+    if isinstance(aliases, Alias):
+        aliases = [aliases]
+    aliases = [alias.full_address for alias in aliases]
+    Users.objects.filter(email__in=aliases).delete()
 
 
 @events.observe("GetStaticContent")