Yefeng,
We have had similar issues when replying to guest messages from email. It is super important to have timely, accurate, and personalized messages to your guests in order to create a strong guest experience and build your brand as a host.
We reported this issue to Airbnb last week and they are working on creating a fix.
In the meantime, my suggestion would be to use the Airbnb website or the Airbnb mobile app in the meantime as the messaging seems to be working just fine on both of those, and you can see your message show up in the message thread right away.
JT