Validate Mail

function validate_mail($email){
    $mailparts=explode("@",$email);
    $hostname = $mailparts[1];
    // validate email address syntax
    $exp = "/^[a-z\'0-9]+([._-][a-z\'0-9]+)*@([a-z0-9]+([._-][a-z0-9]+))+$/i";
    $b_valid_syntax=preg_match($exp, $email);
    // get mx addresses by getmxrr
    $b_mx_avail=getmxrr( $hostname, $mx_records, $mx_weight );
    $b_server_found=0;
    if($b_valid_syntax && $b_mx_avail)
    {
        // copy mx records and weight into array $mxs
        $mxs=array();
        for($i=0;$i<count($mx_records);$i++)
        {
            $mxs[$mx_weight[$i]]=$mx_records[$i];
        }
        // sort array mxs to get servers with highest prio
        ksort ($mxs, SORT_NUMERIC );
        reset ($mxs);
        while (list ($mx_weight, $mx_host) = each ($mxs) )
        {
            if($b_server_found == 0)
            {
                $code = CheckMX($mx_host, $email);
                if ($code == 451)
                    $code = CheckMX($mx_host, $eMail);
                if ($code == 250)
                    $b_server_found=1;
            }
        }
    }
    return $b_server_found;
}
function CheckMX($mx_host, $eMail)
{
    $code = 0;
    $fp = @fsockopen($mx_host, 25, $errno, $errstr, 2);
    if ($fp)    {
        senda_command($fp, 'HELO wiset.it');
        senda_command($fp, 'MAIL FROM:<noreply@wiset.it>');
        $erg = senda_command($fp, 'RCPT TO:<'.$eMail.'>');
        fclose($fp);
        $code = intval(substr($erg, 0, 3));
    }
    return $code;
}
function senda_command($fp, $out)
{
    fwrite($fp, $out . "\r\n");
    return geta_data($fp);
}

function geta_data($fp)
{
    $s="";
    stream_set_timeout($fp, 2);
    for($i=0;$i<2;$i++)
        $s.=fgets($fp, 1024);
    return $s;
}
// support windows platforms
if (!function_exists ('getmxrr') ) {
  function getmxrr($hostname, &$mxhosts, &$mxweight) {
    if (!is_array ($mxhosts) ) {
      $mxhosts = array ();
    }
    if (!empty ($hostname) ) {
      $output = "";
      @exec ("nslookup.exe -type=MX $hostname.", $output);
      $imx=-1;

      foreach ($output as $line) {
        $imx++;
        $parts = "";
        if (preg_match ("/^$hostname\tMX preference = ([0-9]+), mail exchanger = (.*)$/", $line, $parts) ) {
          $mxweight[$imx] = $parts[1];
          $mxhosts[$imx] = $parts[2];
        }
      }
      return ($imx!=-1);
    }
    return false;
  }
}