diff --git a/install_postfix_advanced.sh b/install_postfix_advanced.sh
index 2be6542..19df54f 100755
--- a/install_postfix_advanced.sh
+++ b/install_postfix_advanced.sh
@@ -2911,8 +2911,13 @@ fi
 cat <<EOF >> /etc/postfix/main.cf
 # Policyd-Weight
    #check_policy_service inet:127.0.0.1:12525,
+# ---------------------------------------------------------------------------------
+# DEPRECATED permit_mx_backup
+#
+# warning: support for restriction "permit_mx_backup" will be removed from Postfix;
 # permit Backup MX
-   permit_mx_backup,
+#   permit_mx_backup,
+# ---------------------------------------------------------------------------------
 # permit, if all restrictions so far passed
    permit
 
@@ -2953,8 +2958,13 @@ smtpd_relay_restrictions =
 # managed by the verify(8) server; see http://www.postfix.org/ADDRESS_VERIFICATION_README.html
 # for more details
    reject_unverified_recipient,
+# ---------------------------------------------------------------------------------
+# DEPRECATED permit_mx_backup
+#
+# warning: support for restriction "permit_mx_backup" will be removed from Postfix;
 # permit Backup MX
-   permit_mx_backup,
+#   permit_mx_backup,
+# ---------------------------------------------------------------------------------
 # permit, if all restrictions so far passed
    permit