Ask HN: Choosing a free webmail solution

Seeing as Google's Inbox will be going away this year, I've been trying to identify an alternative webmail solution.

I know a lot of the features of Inbox are being ported to Gmail, but for me Gmail's UI is just really unpleasant to use. I want something that has Inbox's sleekness and minimalism.

After looking around though, it looks like Inbox is pretty unique, with other free services looking seriously out-dated and cluttered. Does anyone have any recommendations (other than self-hosting) of achieving an experience anything like Inbox?