code: def _send(self, messages):
          
          if len(messages) == 1:
              to_send = self._build_message(messages[0])
              if to_send is False:
                  # The message was missing recipients.
                  # Bail.
                  return False
          else:
              pm_messages = list(map(self._build_message, messages))
              pm_messages = [m for m in pm_messages if m]
              if len(pm_messages) == 0:
                  # If after filtering, there aren't any messages
                  # to send, bail.
                  return False
              to_send = PMBatchMail(messages=pm_messages)
          try:
              to_send.send(test=self.test_mode)
          except:
              if self.fail_silently:
                  return False
              raise
          return True
docs: A helper method that does the actual sending.