[Mail Validation] Use SMTP to validate eMail Address #php #function #mailcheck

doSMTPValidation.php

/* ------------------------------------------------------------------------------ */
/* [Mail Validation] Use SMTP to validate eMail Address #php #function #mailcheck */
/* ------------------------------------------------------------------------------ */

function doSMTPValidation($email, $probe_address='', $debug=false) {
  $output = '';
  if (!$probe_address) $probe_address = $_SERVER['SERVER_ADMIN'];
  if (preg_match('/^([a-zA-Z0-9\._\+-]+)\@((\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,7}|[0-9]{1,3})(\]?))$/', $email, $matches)) {
    $user = $matches[1];
    $domain = $matches[2];
    if (function_exists('checkdnsrr')) {
      if (getmxrr($domain, $mxhosts, $mxweight)) {
        for ($i=0;$i<count($mxhosts);$i++) {
          $mxs[$mxhosts[$i]] = $mxweight[$i];
        }
        asort($mxs);
        $mailers = array_keys($mxs);
      } elseif (checkdnsrr($domain, 'A')) {
        $mailers[0] = gethostbyname($domain);
      } else {
        $mailers=array();
      }
      $total = count($mailers);
      if ($total > 0) {
        for ($n=0; $n < $total; $n++) {
          if ($debug) { $output .= 'Checking server '.$mailers[$n].'...'.PHP_EOL; }
          $connect_timeout = 2;
          $errno = 0;
          $errstr = 0;
          if (preg_match('/^([a-zA-Z0-9\._\+-]+)\@((\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,7}|[0-9]{1,3})(\]?))$/', $probe_address,$fakematches)) {
            $probe_domain = str_replace('@', '',strstr($probe_address, '@'));
            if ($sock = @fsockopen($mailers[$n], 25, $errno , $errstr, $connect_timeout)) {
              $response = fgets($sock);
              if ($debug) { $output .= 'Opening up socket to '.$mailers[$n].'... Success!'.PHP_EOL; }
              stream_set_timeout($sock, 5);
              $meta = stream_get_meta_data($sock);
              if($debug) { $output .= $mailers[$n].' replied: '.$response.PHP_EOL; }
              $cmds = array(
                'HELO '.$probe_domain,
                'MAIL FROM: <'.$probe_address.'>',
                'RCPT TO: <'.$email.'>',
                'QUIT',
              );
              if (!$meta['timed_out'] && !preg_match('/^2\d\d[ -]/', $response)) {
                $code = trim(substr(trim($response),0,3));
                if ($code=='421') {
                  $error = $response;
                  break;
                } else {
                  if ($response=='' || $code=='') {
                    $code = '0';
                  }
                  $error = 'Error: '.$mailers[$n].' said: '.$response.PHP_EOL;
                  break;
                }
                break;
              }
              foreach ($cmds as $cmd) {
                $before = microtime(true);
                fputs($sock, $cmd."\r\n");
                $response = fgets($sock, 4096);
                $t = 1000*(microtime(true)-$before);
                if ($debug) { $output .= $cmd.PHP_EOL.$response.'('.sprintf('%.2f', $t).' ms)'.PHP_EOL; }
                if (!$meta['timed_out'] && preg_match('/^5\d\d[ -]/', $response)) {
                  $code = trim(substr(trim($response),0,3));
                  if ($code <> '552') {
                    $error = 'Unverified address: '.$mailers[$n].' said: '.$response;
                    break 2;
                  } else {
                    $error = $response;
                    break 2;
                  }
                }
              }
              fclose($sock);
              if ($debug) { $output .= 'Succesful communication with '.$mailers[$n].', no hard errors, assuming OK'.PHP_EOL; }
              break;
            } elseif ($n == $total-1) {
              $error = 'None of the mailservers listed for '.$domain.' could be contacted';
              $code = '0';
            }
          } else {
            $error = 'The probe_address is not a valid mail.';
          }
        }
      } elseif ($total <= 0) {
        $error = 'No usable DNS records found for domain '.$domain;
      }
    }
  } else {
    $error = 'Address syntax not correct';
  }
  if ($debug) {
    print nl2br(htmlentities($output));
  }
  if (!isset($code)) { $code = 'n.a.'; }
  if (isset($error)) return array($error, $code); else return true;
}