Haven't seen his answer here yet, but I use Zoho. It has a free tier IIRC and supports custom domain.

Not sure how private it is, tho.

I use Tutanota I think it's a really good private email client.

I switched to hosting my own inbound mail. I mostly switched because after trying a few providers they almost all dropped some email that I wanted (not Spam, completely dropped) so I set up my own. It is quite nice to have full control over configuration, filtering, backups and whatever else.

Right now I am using a paid rely to send, but maybe I'll see how my IP's reputation at some point.

Paid Proton Mail with my own domain name and own PGP keypair. Although it now has a way to securely search mail, I use the bridge service to allow Betterbird mail to sync my mail to my PC for searching.

Migadu they are super affordable. Great service. Privacy focused.

ProtonMail because they're at the very least non-intrusive and don't have a track record of snooping through emails, google im looking at you mf

If I remember correctly cock.li is also hosting some really bad Nazi domains and has apparently no problem with that...

iCloud Mail. I have a Proton account, but the app takes several seconds to load and show me my messages on my phone and I hate the delay. Plus, as of iOS 17, Mail now autofills email verification codes and delete the email afterwards. Plus Mail is built into Siri and all that jazz, so it sometimes shows possible events that I can add to the calendar. So convenient.

For the Proton people. I learnt about a guy that ended up in a US court and they asked proton for all his emails and the handed them right away, no questions asked.

I use disroot.