/**
  * @param Newsletter $newsletter
  */
 public function sendNewsletter(Newsletter $newsletter, $languageKey = NULL)
 {
     $client = new Client();
     try {
         $bodyTemplate = $this->convertTemplatesToGoTemplates($newsletter->getHtmlContent());
         $bodyTemplate = str_replace('href="SHOWINBROWSER"', '{{ .showInBrowser }}', $bodyTemplate);
         $bodyTemplate = str_replace('href="UNSUBSCRIBE"', '{{ .unsubscribeUri }}', $bodyTemplate);
         $placeholdersInBodyTemplate = $this->foundPlaceholdersInLastProcessedTemplate;
         $senderEmailTemplate = $this->convertTemplatesToGoTemplates($newsletter->getSenderEmailTemplate() ?: '*****@*****.**');
         $replyToEmailTemplate = $senderEmailTemplate;
         if ($newsletter->getReplyToEmailTemplate()) {
             $replyToEmailTemplate = $this->convertTemplatesToGoTemplates($newsletter->getReplyToEmailTemplate());
         }
         $request = array('RecipientsList' => $newsletter->getReceiverGroup()->getCacheFileName($languageKey), 'Templates' => array('SubjectTemplate' => $this->convertTemplatesToGoTemplates($newsletter->getSubject()), 'BodyTemplate' => $bodyTemplate, 'ReceiverEmailTemplate' => $this->convertTemplatesToGoTemplates($newsletter->getReceiverEmailTemplate() ?: '{email}'), 'ReceiverNameTemplate' => $this->convertTemplatesToGoTemplates($newsletter->getReceiverNameTemplate() ?: '{firstName} {lastName}'), 'SenderEmailTemplate' => $senderEmailTemplate, 'SenderNameTemplate' => $this->convertTemplatesToGoTemplates($newsletter->getSenderNameTemplate() ?: 'Newsletter'), 'ReplyToEmailTemplate' => $replyToEmailTemplate, 'LinkTemplates' => array('unsubscribeUri' => array('EncryptionKey' => $this->hmacUrlSecret, 'BaseLink' => $newsletter->getUnsubscribeLink(), 'Parameters' => ['email']), 'showInBrowser' => array('EncryptionKey' => $this->hmacUrlSecret, 'BaseLink' => $newsletter->getNewsletterLink(), 'Parameters' => $placeholdersInBodyTemplate))));
         $blacklistFileName = $newsletter->getReceiverGroup()->getUnsubscribeList()->getUnsubscribeFileName();
         if (file_exists($blacklistFileName)) {
             $request['Blacklist'] = $blacklistFileName;
         }
         $response = $client->post(rtrim($this->sendingApiUri, '/') . '/' . $this->authToken . '/newsletter/' . $newsletter->getIdentifier() . '/send', array('body' => json_encode($request)));
     } catch (RequestException $e) {
         $errorMessage = 'There was an error communicating with the newsletter API -- HTTP Status Code: ' . $e->getCode();
         if ($e->hasResponse()) {
             $errorMessage .= "\nResponse Body:\n" . $e->getResponse()->getBody()->__toString();
         }
         throw new \Exception($errorMessage, 1431428827, $e);
     }
 }