I heavily use IMAP flags and evolution's virtual folders to nicely group/tag things, rather than IMAP folders. I also use imapfilter to automatically add IMAP flags to messages, and only add 'inbox' to important emails. This keeps my inbox small and tidy, and all my automated stuff goes to other virtual folders.
Unfortunately, I am not aware of any mobile email clients (at least on iOS) that support this workflow, so I do very little email, other than some passive reading on my mobile device.
As a heavy emacs user, mu4e has intrigued me, but I haven't experimented enough with it to move my workflow. For work, I unfortunately have to deal with a lot of html email, calendar invitations, and other non-sense, that evolution handles quite well.