Mailgun\Messages\BatchMessage::sendMessage PHP Method

    public function sendMessage($message = [], $files = [])
    {
        if (count($message) < 1) {
            $message = $this->message;
            $files = $this->files;
        }
        if (!array_key_exists('from', $message)) {
            throw new MissingRequiredMIMEParameters(ExceptionMessages::EXCEPTION_MISSING_REQUIRED_MIME_PARAMETERS);
        } elseif (!array_key_exists('to', $message)) {
            throw new MissingRequiredMIMEParameters(ExceptionMessages::EXCEPTION_MISSING_REQUIRED_MIME_PARAMETERS);
        } elseif (!array_key_exists('subject', $message)) {
            throw new MissingRequiredMIMEParameters(ExceptionMessages::EXCEPTION_MISSING_REQUIRED_MIME_PARAMETERS);
        } elseif (!array_key_exists('text', $message) && !array_key_exists('html', $message)) {
            throw new MissingRequiredMIMEParameters(ExceptionMessages::EXCEPTION_MISSING_REQUIRED_MIME_PARAMETERS);
        } else {
            $message['recipient-variables'] = json_encode($this->batchRecipientAttributes);
            $response = $this->restClient->post($this->endpointUrl, $message, $files);
            $this->batchRecipientAttributes = [];
            $this->counters['recipients']['to'] = 0;
            $this->counters['recipients']['cc'] = 0;
            $this->counters['recipients']['bcc'] = 0;
            unset($this->message['to']);
            array_push($this->messageIds, $response->http_response_body->id);
        }
    }