Einfacher E-Mail test für PHP

function verify_email($email) {
  $success = false;
  // basic $email adress validation
  if(preg_match("/^[0-9a-z]([.0-9a-z_\-]+)*@(([0-9a-z\-]+\.)+[0-9a-z]{2,4})$/i" , $email)) {
    // get domain from adress
    list($user,$domain) = split('@',$email);
    // get MX hosts
    if( dns_get_mx($domain, &$mxhosts)) {
      // test connection to mx servers
      foreach ($mxhosts as $mxhost) {
        if(fsockopen($mxhost,25,$errno,$errstr,15)) {
          $success = true;
          break;
        }
      }
    }
  }
  return $success;
}