docs: def reply_to(self, value):
          """The reply to email address
  
          :param value: The reply to email address
          :type value: ReplyTo, str, tuple
          """
          if isinstance(value, str):
              value = ReplyTo(value, None)
          if isinstance(value, tuple):
              value = ReplyTo(value[0], value[1])
          self._reply_to = value