public function import(string $gpgKey): string
    {
        try {
            $gnupg = new \Crypt_GPG($this->options);
            /** @var array<string, string> $data */
            $data = $gnupg->importKey($gpgKey);

            return $data['fingerprint'];
        } catch (\PEAR_Exception $ex) {
            throw new GPGMailerException(
                'Could not import public key: ' . $ex->getMessage(),
                $ex->getCode(),
                $ex
            );
        }
    }