#! /usr/local/bin/php
<?php
/*
 * Copyright (C) 2003-2004 Pawel Foremski <pjf@gna.org>
 *
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License 
 * as published by the Free Software Foundation; either 
 * version 2 of the License, or (at your option) any later 
 * version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 ***
 *
 * $Id: mfdnscheck.php,v 1.1 2004/07/05 18:27:21 pavcio Exp $
 *
 */

error_reporting(0);

if ($_ENV['NOMFDNSCHECK'] !== NULL) exit(0);

/* get envelope sender address */
list($mail_login, $mail_domain) = split('@', $_ENV['SMTPMAILFROM'], 2);
if (!$mail_domain ) exit(); /* no domain to check */

/*
  From PHP Manual:

    "according to RFC 2821 when no mail exchangers are listed,
    hostname itself should be used as the only mail exchanger with a
    priority of 0"

  so we check DNS_A too
*/

/* get DNS record */
$dnsrec = dns_get_record($mail_domain, DNS_A | DNS_MX);

if (!is_array($dnsrec) || count($dnsrec) ) exit(); /* query failed or domain exists */

fwrite(STDERR, "non existing envelope sender domain: $mail_domain\n");
exit("E552 sorry, your envelope sender domain must exists (#5.7.1)\n");

?>