diff --git a/bundles/mailserver/items.py b/bundles/mailserver/items.py
index 2ea9d8b..f7c6598 100644
--- a/bundles/mailserver/items.py
+++ b/bundles/mailserver/items.py
@@ -15,10 +15,7 @@ setup = '''
     CREATE TABLE users (
         "id" BIGSERIAL PRIMARY KEY,
         "name" varchar(255) NOT NULL,
-        "domain_id" BIGSERIAL NOT NULL,
-        CONSTRAINT "fk_domain"
-            FOREIGN KEY("domain_id") 
-                REFERENCES domains("id"),
+        "domain_id" BIGSERIAL REFERENCES domains(id),
         "password" varchar(255) NULL,
         "redirect" varchar(255) DEFAULT NULL
     );