I’m using Infomaniak Mail and am fairly happy so far. They are based in Switzerland and I get custom domain + 5 user accounts for 1.50 EUR/month. I’ve tried other providers but coming from Gmail I like that their webmail displays email conversation like Google does whereas most other providers just run rainloop or roundcube where threading support isn’t quite the same.

Their android app is open source too and can be installed from fdroid. It can be a bit sluggish sometimes though, but K9mail/Thunderbird works fine too.

I can recommend this too. I got the WiFi version. Integrates beautifully with home assistant including motion/person detection.

That’s what I do. The beauty of wireguard is that it won’t respond at all if you don’t send the right key. So from the outside it will appear as if none of your ports are open.