diff --git a/mail/docker-mailserver.yaml b/mail/docker-mailserver.yaml
index 9645373..748103e 100644
--- a/mail/docker-mailserver.yaml
+++ b/mail/docker-mailserver.yaml
@@ -5,6 +5,7 @@ metadata:
   namespace: mail
 immutable: false
 data:
+  DOMAINNAME: "undercloud.dev"
   OVERRIDE_HOSTNAME: "mail.apps.undercloud.dev"
 
   SSL_TYPE: "manual"
@@ -40,7 +41,6 @@ data:
 
   POSTMASTER_ADDRESS: "postmaster@localhost.localdomain"
 ---
----
 apiVersion: v1
 kind: ConfigMap
 metadata: