diff --git a/ceod/model/User.py b/ceod/model/User.py
index dcef636..ff7671a 100644
--- a/ceod/model/User.py
+++ b/ceod/model/User.py
@@ -70,6 +70,7 @@ class User:
 
         self.ldap_srv = component.getUtility(ILDAPService)
         self.krb_srv = component.getUtility(IKerberosService)
+        self.base_domain = cfg.get('base_domain')
 
     def to_dict(self, get_forwarding_addresses: bool = False) -> Dict:
         data = {
@@ -105,6 +106,8 @@ class User:
         return self._is_club
 
     def add_to_ldap(self):
+        if not self.mail_local_addresses:
+            self.mail_local_addresses = [f'{self.uid}@{self.base_domain}']
         self.ldap_srv.add_user(self)
 
     def remove_from_ldap(self):
diff --git a/tests/ceod/api/test_members.py b/tests/ceod/api/test_members.py
index 21c360f..b936d0f 100644
--- a/tests/ceod/api/test_members.py
+++ b/tests/ceod/api/test_members.py
@@ -63,6 +63,7 @@ def test_api_create_user(cfg, create_user_resp, mock_mail_server):
             "is_club_rep": False,
             "program": "Math",
             "terms": ["s2021"],
+            "mail_local_addresses": ["test_1@csclub.internal"],
             "forwarding_addresses": ['test_1@uwaterloo.internal'],
             "password": "krb5"
         }},