diff --git a/modoboa/lib/authbackends.py b/modoboa/lib/authbackends.py
index bbe5f0308..a4122b497 100644
--- a/modoboa/lib/authbackends.py
+++ b/modoboa/lib/authbackends.py
@@ -84,18 +84,17 @@ try:
                 if grp.strip() in ldap_user.group_names:
                     group = "DomainAdmins"
                     break
-            if group == "SimpleUsers":
-                lpart, domain = split_mailbox(username)
-                if domain is None:
-                    # Try to find associated email
-                    email = None
-                    for attr in ['mail', 'userPrincipalName']:
-                        if attr in ldap_user.attrs:
-                            email = ldap_user.attrs[attr][0]
-                            break
-                    if email is None:
-                        return None
-                    username = email
+            lpart, domain = split_mailbox(username)
+            if domain is None:
+                # Try to find associated email
+                email = None
+                for attr in ['mail', 'userPrincipalName']:
+                    if attr in ldap_user.attrs:
+                        email = ldap_user.attrs[attr][0]
+                        break
+                if email is None and group == "SimpleUsers":
+                    return None
+                username = email
             user, created = User.objects.get_or_create(
                 username__iexact=username,
                 defaults={