i have been using posteo.de for the last decade with no problems at all. Exactly the feature set you use. I only recently started to use their Caldav stuff which works.

I recommend them.

Same here. I don't want a custom domain for certain things, and Posteo (posteo.de) was good. Posteo increased the mailbox storage to 4 GB recently and the default number of free aliases too. I'm satisfied that it's run by a team and not by one person (the low bus factor mentioned above). At EUR 1 per month, it's way cheaper than Fastmail for multiple mailboxes across family members and provides a lot more value, IMO.

Thanks for that recommendation. It is simple and yes it is much easier to just get reading than Koreader