I do, I host my own mail server.

Technically it's not very challenging. The problem is the total dominance of a few actors and a lot of spammers.

I haven't had spam issues since using a catch-all and giving everyone a unique address, blocking ones that receive spam

Won't work if you need a fixed address on a business card or something, but in case you don't...

Waiting for the day they catch on. Then it's time for a challenge-response protocol I guess