Tuta guarantees your data stays private for free & without ads. Quantum-resistant encryption makes Tuta the best secure technology solution to protect your privacy.
Tuta is a end-to-end-encryption mail and calendar provider. They recently wrote a good blog-post about changing to european services.
Using Thunderbird as opposed to tuta's quite barebones client:
delayed messaging
message scheduling
local backup of mails
no email import
desktop app failures (happens quite often to me that I just can't log in)
Not to mention other external QoL functionalities like a home assistant tablet being able to display a family calendar and being able to automate based off of events
Tuta's discount is tempting, but I've also seen StartMail doing 50% off lately. Definitely feels like a good time to test a couple out, especially if you care more about UX than just encryption.
I have been using mailbox's light (1€/month) tier, which doesn't include the calendar, so I can't really tell you about its quality.
What I can tell you though, is that it has worked great with K-9 and Geary and everyone I have emailed has recieved it and it hasn't gone to any spam folders or such.
Posteo has no custom domain support, deal breaker for me. As far as I understand they don't support IMAP in order to keep their encryption working, and I believe others like Proton do the same thing. Since their webapp is good and they even have an official client on Fdroid, I don't think it's a big deal
For people who want custom domain support, as well as SMTP/IMAP, but still euro-based, Nubo may be more what you're looking for if you're OK with dealing with a newer company.
Just started a test subscription with posteo... I'm rather disappointed they don't allow to view the email previews in vertical columns. Their layout is horizontal only and can't be changed. It's a very small pet peeve, but i wasn't expecting not being able to change that :(