code: def _messageFromSender(self, sender, messageID):
          
          return self.store.findUnique(
              _QueuedMessage,
              AND(_QueuedMessage.senderUsername == sender.localpart,
                  _QueuedMessage.senderDomain == sender.domain,
                  _QueuedMessage.messageID == messageID),
              default=None)
docs: Locate a previously queued message by a given sender and messageID.