Hmmmmm would it work like DMs in Damus? Like anyone can send to you (requests) but you have to accept it? Otherwise spam will be prevalent.

Paid relays might be handy here to to combat spam

It’s kind of there already. Nostr private notes are end to end encrypted and not readable by any centralized third party.

How about just kill email?

Def possibility I’d assume. Considering we have encrypted DMs now. I feel like that’s not too many steps from a full fledged email client.