Does anyone have any thoughts on the security (or other) implications of all your email for services in which you sign up using Apple SignIn now being relayed through Apple's mail servers?

It seems like a great way for Apple to hoover up a heap information they probably don't need.

I also wonder how they are going to combat bounces and send back a usable error message. While they can perhaps do useful things with say a mailbox full bounce they are probably going to have to hide or at least obfuscate some other kinds of bounces.