protected function checkValidEmail($email) {
    if (function_exists('mailparse_rfc822_parse_addresses')) {
      $parsed = mailparse_rfc822_parse_addresses($email);
      if (count($parsed) > 0 && array_key_exists('address', $parsed[0])) {
        $email = $parsed[0]['address'];
      } else {
        return false;
      }
    }
    return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
  }