Fastmail is good, I've used it a few years.
Frustrating that it was designed so badly and I don't think there's a way to fix it without fixing protocols really and doing E2E encryption and signing with keys only on devices, even then you depend on all the code handling that to be secure, and nobody on the other side to store plain text of your encrypted emails (which they must be able to see/get after all).
https://www.fastmail.com/blog/fastmail-offers-eu-data-region...
> If what you need is a guarantee that your data remains only in the EU, we don’t have that, and we’d rather tell you directly than let you assume otherwise.
Vouched, no idea why this comment was dead.