[k2enemy]

Mutt cannot do multiple folders and keep state.

Coincidentally, I used to use sup and it is my favorite mail client that I've used. At the time there was no way to sync changes back to maildir or some format that IMAP could sync. Is that still the case?

[rakoo]

No, maildir syncback has been merged for some time already (https://github.com/sup-heliotrope/sup/wiki/Using-sup-with-ot...): changes in sup are sent back to maildir, which is synchronized back to IMAP as usual !

[em-bee]

it is worth pointing out that very recently sup development has picked up again by a few contributors