code: public function createMessageFromTemplateEntity(EmailTemplate $template, array $parameters = array())
      {
          $subject = $this->renderStringTemplate($template->getSubject(), $parameters);
          $recipient = $this->renderStringTemplate($template->getRecipient(), $parameters);
          $body = $this->renderStringTemplate($template->getBody(), $parameters);
          $sender = $template->getSender() ?: $this->defaultSender;
  
          $message = new \Swift_Message($subject, $body, $template->getMimeType());
          $message->setFrom($sender)
                  ->setSender($sender)
                  ->setTo($recipient);
  
          if ($template->hasCc()) {
              $message->setCc($template->getCc());
          }
  
          if ($template->hasAltBody()) {
              $altBody = $this->renderStringTemplate($template->getAltBody(), $parameters);
              $message->addPart($altBody, $template->getAltMimeType());
          }
  
          return $message;
      }
docs: Create Message from an EmailTemplate entity
  
  @param \Orkestra\Bundle\ApplicationBundle\Entity\EmailTemplate $template
  @param array $parameters An array of parameters to pass to the the templating engine
  @return \Swift_Message