/**
  * Add standard variables to event before firing.
  *
  * @param  \App\Events\Event $event
  * @return \App\Events\Event
  */
 protected function filterEvent($event)
 {
     return $event->set(['id' => $this->request->get('id'), 'timestamp' => $this->request->get('timestamp'), 'email' => $this->request->get('recipient'), 'domain' => $this->request->get('domain'), 'headers' => $this->request->get('message-headers')]);
 }