[kick]

Worst possible case you can drop the messages from a domain, which is how federated systems already work.

There's no reason to ever revoke control for messaging systems, though, genuinely: imagine if your e-mail address could be taken on a whim by anyone. It can be! But you'd never want to revoke control of a domain rather than just marking it as spam or illegal and dropping messages from it. It functions as an inbox more than it functions as an outbox.

Addressing space should be permanent.