diff --git a/mail_sender_router/start.sh b/mail_sender_router/start.sh
index 4722d6f..ea51925 100755
--- a/mail_sender_router/start.sh
+++ b/mail_sender_router/start.sh
@@ -22,13 +22,10 @@ fi
 
 if [ -n "$REPLACE_EMPTY_WITH" ]; then
   echo "replacing empty sender with $REPLACE_EMPTY_WITH"
-    # postconf -e "smtp_header_checks = regexp:/etc/postfix/header_check"
-    # postconf -e "local_header_rewrite_clients = static:all"
-    # echo "/From: <>/ REPLACE From: $REPLACE_EMPTY_WITH" > /etc/postfix/header_check
 
   postconf -e "sender_canonical_maps = regexp:/etc/postfix/sender_canonical_maps"
   postconf -e "canonical_classes = envelope_sender, header_sender"
-  echo "/^.*$/ $REPLACE_EMPTY_WITH" > /etc/postfix/sender_canonical_maps
+  echo "/^[^@]*$/ $REPLACE_EMPTY_WITH" > /etc/postfix/sender_canonical_maps
 fi
 
 while [ -n "$(eval echo \$EMAIL_${counter})" ]; do