The closest you can get, afaik, is this:
function valid_email( $email)
{
$ok = TRUE;
$ok = eregi( "[_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3}$", $email, $check);
$ok = getmxrr(substr(strstr($check[0], '@'), 1), $dummy);
if($ok === false) {
$host = substr($email, strpos($email, '@') + 1);
if(gethostbyname($host) != $host) {
$ok = true;
}
}
return $ok;
}