diff --git a/.env.sample b/.env.sample
index cde58e6..e206841 100644
--- a/.env.sample
+++ b/.env.sample
@@ -8,6 +8,7 @@ SERVE_FROM_DOMAIN=${DOMAIN}
 MAILMAN_ADMIN_EMAIL=admin@example.com
 
 SMTP_HOST=mail_example_com_smtp # mailu smtp
+SMTP_NETWORK=mail_example_com_default # mailu network
 SMTP_PORT=25
 
 SECRET_DB_PASSWORD_VERSION=v1
diff --git a/compose.yml b/compose.yml
index b4a957b..edba726 100644
--- a/compose.yml
+++ b/compose.yml
@@ -9,6 +9,7 @@ services:
       - "mailman-core:/opt/mailman/"
     networks:
       - internal
+      - shared_mailu_network
     secrets:
       - db_password
       - django_secret_key
@@ -112,6 +113,9 @@ networks:
   internal:
   proxy:
     external: true
+  shared_mailu_network:
+    external: true
+    name: ${SMTP_NETWORK}
 
 volumes:
   db: