public function Export($fileFormat = \ElasticEmailEnums\ExportFileFormats::Csv, $rule = null, array $emails = array(), $compressionFormat = \ElasticEmailEnums\CompressionFormat::None, $fileName = null) {
        return $this->sendRequest('contact/export', array(
                    'fileFormat' => $fileFormat,
                    'rule' => $rule,
                    'emails' => (count($emails) === 0) ? null : join(';', $emails),
                    'compressionFormat' => $compressionFormat,
                    'fileName' => $fileName
        ));
    }