Whew, that took me a while to setup mu4e with multiple accounts correctly. But now it works like a pro. I even wrote a macro to create the contexts: https://github.com/steckerhalter/steckemacs.el/blob/2e90a717066cbfa9408b5d9ab19d09a0fee099ab/steckemacs.el#L1474
I'm using mbsync for the imap sync this time instead of offlineimap (which caused too much weird errors). If you have questions, feel free to ask... #emacs