code: def save(self, folder):
          
          if not self.account:
              raise ValueError('%s must have an account' % self.__class__.__name__)
          res = self.account.bulk_create(items=[self], folder=folder, message_disposition=SAVE_ONLY)
          if res and isinstance(res[0], Exception):
              raise res[0]
          res = list(self.account.fetch(res)) # retrieve result
          if res and isinstance(res[0], Exception):
              raise res[0]
          return res[0]
docs: save reply/forward and retrieve the item result for further modification,
          you may want to use account.drafts as the folder.