Love Tutanota and been using it for some time. I do wish I could access it using mutt though, like if they supported some kind of bridge. I know they have security concerns with this, but it would actually be more secure for me, since I'd not have to access it directly on every device, leaving active email tabs open. I'd just keep all email use on my home server, leaving mutt up in the tmux session which I'm already in all day, and it'd be as secure as anything else I can only get to via SSH. It's also annoying needing a web browser open when I otherwise don't have use of one, especially on low end hardware like a Raspberry Pi.