[czottmann]

I can recommend https://fastmail.fm/ which has been a really solid experience for me over the last few months. The UI is quite nice—see Mike Masnick's write-up for some screenshots.[^1]

Their servers are located in the US, tho, which might be a cause of concern for some—but that wasn't part of the question. (Personally, I will be probably moving my mails off of FM for that particular reason.)

[^1]: http://www.maxmasnick.com/2013/07/19/fastmail/

[workhere-io]

Here's another review of FastMail (shameless plug): http://blog.workhere.io/my-experience-with-fastmail-as-a-gma...