Today, we visit tencent who has around 1 Billion email users. The senior engineer said that
New version of tencent mail system has supported EAI.

It is a very good news. In Jan. 2018, when UASG team outreached tencent, they promised that they will implement EAI after 1 year! Now it is that promise comes true. Thanks tencent. If you have any interest, pls go to http://wx.mail.qq.com/ for a test.