Validate Email Domain in PHP

        $email_domain = preg_replace('/^.+?@/', '', $email).'.';
 if(!checkdnsrr($email_domain, 'MX') && !checkdnsrr($email_domain, 'A')){
    echo $email.' doesnot exist';
 } else {
  echo 'Email Domain '.$email_domain.' exists! ';
 }