public function sendRaw($rawMessage, array $to = array(), $mailFrom = NULL, $helo = NULL, $clientAddress = NULL){
        return $this->request('send-raw', array(
            'raw_message' => $rawMessage,
            'to' => $to,
            'mail_from' => $mailFrom,
            'helo' => $helo,
            'client_address' => $clientAddress
        ));
    }