I started Netease's "personal mail" on 163, and then I tried to send an email to myself. Why didn't I get the SMS reminder?

I have used my 163 free mail for many years. I used my password when I registered, and it has never been stolen. OUTLOOK usually sends and receives e-mail messages. Posted on the Internet yesterday, there was a hint of "safety factor". A look is to verify the mobile phone number. Say it's free, because it's better to believe it than to test Netease. Check around 4: 30 pm. However, around 1 1:30 in the evening, my mobile phone suddenly received a message saying that my email account in Changzhou was changed to "password prompt answer". So I sent a message on my mobile phone and changed my password. Soon, I will send a text message to charge a service fee of 1 yuan! I have a few questions about this! 1. My email was registered with the same password (almost four years) and has never been stolen. What happened when the mobile phone was stolen immediately after verification? ! 2. I doubt it very much that the prompt is changed to "password prompt question answer". I pay great attention to secrecy. How do others know the registration questions and answers? There are free mailboxes everywhere now. Why do "hackers" steal useless free mail? To sum up, I doubt whether Netease's mobile phone verification of free mail will be another trap!