@jgoerzen reviewed mail providers and the one I use came up on top, Migadu.
https://changelog.complete.org/archives/10711-review-of-reputable-functional-and-secure-email-service

The only thing I wondered was that John criticized Fastmail for being in Australia where the state has far reaching powers and Migadu is in Switzerland, where the state also has far-reaching powers, as far as I know.

The lawyer that keeps popping up in these situations is Steiger, and he wrote about Proton Mail and Threema (in German). The short summary is that Swiss companies must cooperate with the state and the state cooperates with foreign powers. Furthermore, Switzerland forces providers to keep logs for long times and to hand them out when required. It’s not trivial and not automatic, but my assumption is that it slow and thorough. There’s nobody fighting for your rights before a trial, after all.
https://steigerlegal.ch/2021/10/23/urteil-protonmail-buepf-aakd-fda/

I guess what I want to say is that I use them, I like them, but I very much dislike the Swiss privacy fairy dust that Proton Mail, Threema, Migadu and others imply which doesn’t actually exist. In Germany, at least, politicians vote to force providers to keep logs and the constitutional court kicks it out again. Not so in Switzerland. Network analysis is just a legal request away.

I’m not a lawyer and I barely know a thing, of course, and I’m confused and mix the half-remembered things up; so don’t believe me – but also don’t believe them without investigating and understand the implications. Like, maybe the state doesn’t keep logs but it forces every email provider with more than five customers to keep logs? It’s only marginally better. Put every word on a scale.