diff --git a/roles/shell/files/etc/postfix/main.cf b/roles/shell/files/etc/postfix/main.cf
index 83ca36c..00c20b3 100644
--- a/roles/shell/files/etc/postfix/main.cf
+++ b/roles/shell/files/etc/postfix/main.cf
@@ -67,6 +67,7 @@ smtpd_recipient_restrictions =
  reject_non_fqdn_recipient,
  reject_unknown_sender_domain,
  reject_unknown_recipient_domain,
+ reject_unknown_reverse_client_hostname,
  check_policy_service unix:private/policyd-spf,
  reject_rbl_client bl.fmb.la=127.0.1.[24;25;26;27;28],
  reject_rbl_client spam.dnsbl.anonmails.de,