function check_email_mx($email) {
if(
(preg_match('/(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/', $email)) ||
(preg_match('/^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/',$email))
) {
$host = array_pop(explode('@', $email));
if(checkdnsrr($host.'.', 'MX') ) return true;
if(checkdnsrr($host.'.', 'A') ) return true;
if(checkdnsrr($host.'.', 'CNAME') ) return true;
}
return false;
}