/**
 * Executes the get_preview method on the provided messenger.
 *
 *@param EE_Message            $message
 * @param EE_messenger    $messenger
 * @param EE_message_type $message_type
 * @param $test_send
 * @return bool   true means all went well, false means, not so much.
 */
 protected function _do_preview(EE_Message $message, EE_messenger $messenger, EE_message_type $message_type, $test_send)
 {
     if ($preview = $messenger->get_preview($message, $message_type, $test_send)) {
         if (!$test_send) {
             $message->set_content($preview);
         }
         $message->set_STS_ID(EEM_Message::status_sent);
         return true;
     } else {
         $message->set_STS_ID(EEM_Message::status_failed);
         return false;
     }
 }