diff --git a/dockerfile b/dockerfile
index 732d3ad..c3adde7 100644
--- a/dockerfile
+++ b/dockerfile
@@ -195,6 +195,8 @@ RUN postconf -e "maillog_file=/var/log/postfix.log" \
     # Connection defaults to reject where possible/advised
     # Client command restrictions
   && postconf -e "smtpd_client_restrictions=reject_unauth_destination,reject_unauth_pipelining,permit_mynetworks,permit_auth_destination,reject" \
+    # HELO/EHLO restrictions
+  && postconf -e "smtpd_helo_restrictions=permit_mynetworks,reject_invalid_helo_hostname,permit" \
     
 EXPOSE 25 587 993 4190