Why is private mail triggered?

Question

I set up an email service to send some emails, using NetEase’s smtp service. The email contains a connection request to the server, but after a while, I will see a request from 106.38.230.185 in the server log, and I These emails should be private, why are they being requested inexplicably?

Answer 1

Have you used a client to read emails? There may be content detection.

If you want to determine whether it is spam advertising, you must request the content to know.