<?php
require_once('Net/DNSBL.php');

$dnsbl = new Net_DNSBL();
$dnsbl->setBlacklists(array('list.dsbl.org', 'xbl.spamhaus.org', 'sbl.spamhaus.org'));
if？($dnsbl->isListed($_SERVER['REMOTE_ADDR']))？{
？？？？die('block!!');
}

?>