public function encodeString(string $address): string
    {
        $i = strrpos($address, '@');
        if (false !== $i) {
            $local = substr($address, 0, $i);
            $domain = substr($address, $i + 1);

            if (preg_match('/[^\x00-\x7F]/', $local)) {
                throw new AddressEncoderException(sprintf('Non-ASCII characters not supported in local-part os "%s".', $address));
            }

            if (preg_match('/[^\x00-\x7F]/', $domain)) {
                $address = sprintf('%s@%s', $local, idn_to_ascii($domain, 0, INTL_IDNA_VARIANT_UTS46));
            }
        }

        return $address;
    }