code: def push(self, code, msg=None):
          
          if msg is None:
              msg = str(code)
          else:
              msg = '%s %s' % (code, msg)
  
          if not msg.endswith(self.LINE_TERMINATOR):
              msg += self.LINE_TERMINATOR
          self._channel.write(msg)
docs: Send a message to the peer (using the correct SMTP line terminators
          (usually only called from the SMTPSession).