I have seen this approach from other people as well. How do you feel about them knowing your custom domain? Then it’s easier to search for other mail addresses of that domain as well?

I use the aliases from Proton which make me feel a bit more ‘safe’. Downside is that I’m locked into Proton… :)

I tried to selhost via Nextcloud.

It worked on my Android mobile via DAVx5.

My gf wanted it in her google calender, but then I needed to expose my calender to the web which I didn’t want, so I switched to Proton now…