php опpеделить валидность e-mail

function valid_mail ($email) {
  if (eregi("^[_\.0-9a-z-]+@([0-9a-z][0-9a-z-\.]+)\.([a-z]{2,3}$)",
          $email, $check)) {
    if (getmxrr($check[1] . "." . $check[2]) return "Valid";
    else return "No MX for " . $check[1] . "." . $check[2];
  }
  else return "Badly formed address";
}