I recommend notmuch in place of mu/mu4e and msmtp in place of a full-blown smtpd implementation.
I also recommend isync's mbsync over offlineimap
I also recommend isync's mbsync over offlineimap
I primarily use mu4e but want to see changes on my mobile as well as on any remote computer using a web client in a browser.
As far as I know notmuch can just be synchronized to another notmuch instance.
Personally, I don't bother with it. When I have to do mail on my phone, it's usually so limited in scope that I don't need to retain state when I sit down at my main computer. I can imagine that's not for everyone, though.