diff --git a/data/conf/postfix/main.cf b/data/conf/postfix/main.cf
index 237b42635..1dce6a4c7 100644
--- a/data/conf/postfix/main.cf
+++ b/data/conf/postfix/main.cf
@@ -11,6 +11,7 @@ smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
 smtpd_relay_restrictions = permit_mynetworks,
   permit_sasl_authenticated,
   defer_unauth_destination
+smtpd_forbid_bare_newline = yes
 # alias maps are auto-generated in postfix.sh on startup
 alias_maps = hash:/etc/aliases
 alias_database = hash:/etc/aliases
diff --git a/docker-compose.yml b/docker-compose.yml
index 1156854e7..2521e8164 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -298,7 +298,7 @@ services:
             - dovecot
 
     postfix-mailcow:
-      image: mailcow/postfix:1.72
+      image: mailcow/postfix:1.73
       depends_on:
         mysql-mailcow:
           condition: service_started