> but even for that, if you don't care about fancy guis, you're probably still better off running mutt, imap, mu on a shell you have somewhere

I do like fancy GUIs and use roundcube as one option. For me,

> it's still much more portable and easily to handle backup and syncing purposes in different formats.

...the portability is very important. I don't want a new MUA to force me into changing my whole mailstore/MTA chain.