diff --git a/docker-compose.stg.yml b/docker-compose.stg.yml
index d8c46a1e..0851a785 100644
--- a/docker-compose.stg.yml
+++ b/docker-compose.stg.yml
@@ -6,7 +6,7 @@ services:
     environment:
       - RELAYHOST=mailpit.stg.internal
       - RELAYHOST_PORT=1025
-      - ALLOWED_SENDER_DOMAINS=*
+      - ALLOWED_SENDER_DOMAINS=cmctechnologies.com.au
       # --- Gmail SMTP relay settings (uncomment for production) ---
       # - RELAYHOST=smtp-relay.gmail.com
       # - RELAYHOST_PORT=587