diff --git a/core/admin/mailu/internal/nginx.py b/core/admin/mailu/internal/nginx.py
index 4cb503ac..38d9f8d6 100644
--- a/core/admin/mailu/internal/nginx.py
+++ b/core/admin/mailu/internal/nginx.py
@@ -13,6 +13,7 @@ STATUSES = {
     "authentication": ("Authentication credentials invalid", {
         "imap": "AUTHENTICATIONFAILED",
         "smtp": "535 5.7.8",
+        "submission": "535 5.7.8",
         "pop3": "-ERR Authentication failed",
         "sieve": "AuthFailed"
     }),