diff --git a/apps/base/mailgateway/services.yaml b/apps/base/mailgateway/services.yaml
index 3ccbcbf..eddc629 100644
--- a/apps/base/mailgateway/services.yaml
+++ b/apps/base/mailgateway/services.yaml
@@ -49,6 +49,7 @@ metadata:
   namespace: mailgateway
   annotations:
     external-dns.alpha.kubernetes.io/hostname: smtp-in.main.unkin.net
+    purelb.io/service-group: dmz
 spec:
   type: LoadBalancer
   externalTrafficPolicy: Local