diff --git a/smtp-relay/docker-compose.yaml b/smtp-relay/docker-compose.yaml
index c49b79e..c6ff078 100644
--- a/smtp-relay/docker-compose.yaml
+++ b/smtp-relay/docker-compose.yaml
@@ -6,6 +6,7 @@ services:
       - RELAYHOST=${RELAYHOST}
       - RELAYHOST_USERNAME=${RELAYHOST_USERNAME}
       - RELAYHOST_PASSWORD=${RELAYHOST_PASSWORD}
+      - POSTFIX_smtp_tls_security_level=${POSTFIX_smtp_tls_security_level}
       - ALLOWED_SENDER_DOMAINS=${ALLOWED_SENDER_DOMAINS}
       - MASQUERADED_DOMAINS=${MASQUERADED_DOMAINS}
     networks: