I use isync (mbsync), mu, and Emacs for my e-mail needs and it work fine. Both isync and mu4e needed a bit of configuration (and Emacs itself needed one change to stop automatically breaking lines), but it's been working well for years now. I previously used Thunderbird but its editor was garbage, so then I tried a few things (neomutt and I believe something called alpine or something like that) before settling on Emacs. I tried Notmuch, but it didn't work so well with the upstream mailboxes.