public function sendRaw($rawMessage, $fromEmail = NULL, $fromName = NULL, array $to = array(), $async = false, $ipPool = NULL, $sendAt = NULL){
        return $this->request('send-raw', array(
            'raw_message' => $rawMessage,
            'from_email' => $fromEmail,
            'from_name' => $fromName,
            'to' => $to,
            'async' => $async,
            'ip_pool' => $ipPool,
            'send_at' => $sendAt
        ));
    }