code: def get_account_mailbox(self, account_id):
          
          selector = zobjects.Mailbox(id=account_id).to_selector()
          resp = self.request_single('GetMailbox', {'mbox': selector})
  
          return zobjects.Mailbox.from_dict(resp)
docs: Returns a Mailbox corresponding to an account. Usefull to get the
          size (attribute 's'), and the mailbox ID, returns nothing appart from
          that.