Sup has most of the features I need; especially fully keyboard-driven/ vim-like (tried mu4e, but emacs is just not for me..).

However: How could I mark mails as Spam/ Ham and move them into a separate IMAP Folder?

Ideally, I would just tag them with ",s" for Spam and ",h" as Ham, and when synching, the mails are moved (or better copied?) for training.

Best regards, 

Robert