private function assertTrustedIp()
    {
        $baseHost = parse_url($this->serviceUri, PHP_URL_HOST);
        $serviceIp = gethostbyname(
            $baseHost
        );

        if ( ! $this->isTrustedIpAddress($serviceIp)) {
            throw new EmailServiceClientException(
                'The service has an IP that is not trusted ... ' . $serviceIp,
                1503511662
            );
        }
    }