diff --git a/docker-compose.yml b/docker-compose.yml
index c99f2ec..b87a3ca 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -23,6 +23,7 @@ services:
       - GITEA_MAILER_USER=$GITEA_MAILER_USER
       - GITEA_MAILER_FROM=$GITEA_MAILER_FROM
       - GITEA_MAILER_PASSWD=$GITEA_MAILER_PASSWD
+      - GITEA_MAILER_PROTOCOL=$GITEA_MAILER_PROTOCOL
 
     volumes:
       - gitea-app:/data