Tutanota is my first e-mail provider since deGoogling.

ProtonMail didn't have an integrated Calendar (at that time at least) and was more expensive. Fastmail is Australian which is a non-starter from a privacy perspective. Unironically written from the US. Also, more expensive to use your own domain.

Tutanota is €1/mo (billed yearly), lets me use my own domain, has a calendar, and is based in Germany.

Since using it, I realized without the Calendar scanning my Inbox and auto-adding flights and trips and birthdays, I don't use it as much. But I also haven't traveled much since March.

Definitely worth a look if privacy is a goal, and money is an object.