Nothing to do! even with Beta 7 I always find the same problem with the Mail app that is unable to receive and send mail if it is not connected to the Wifi network. I wonder if it is a common problem or just mine and if there is a way to fix it.

The issue is still there! Beta 3 the problem seemed solved but from Beta 4 to 6 it still gives me the same problem if I'm not under Wi-fi network.

I also encountered the same problem with the new iOS17 beta 2. I only see the problem on emails from third party services, those from icloud work instead.