private function checkPort($domain, $port)
 {
     $SMTP = new Smtp();
     $mxRecords = $SMTP->getMXRecords($domain);
     foreach ($mxRecords as $mxRecord) {
         if ($res = @fsockopen($mxRecord, $port, $errCode, $errStr, TIMEOUT / 2)) {
             fclose($res);
             return true;
         }
         Script::write2Log("{$mxRecord} no connect");
     }
     return false;
 }