Evolution is another GUI client I don't have a ton of experience with other than proofing it was stable. It exists.
Unironically the most powerful email clients i know on any platform are retro, mutt or emacs (last time I used notmuch, but there's options). I never bothered to set it up since all the reading and half the writing I do are off my phone these days.
But I don't know the juice is worth the squeeze starting out, that's a bit of a hurdle. I'm really curious on use case, what are you missing?
It's largely a tough nut to crack just because Microsoft is obnoxious about integration. Thunderbird can do it (or used to) in pieces with local AD forest access. I don't know about remote IMAP access, but you can definitely sneaker net export. It's the weird formatting on the import side I'm fighting.
I saw someone piping something to local programs through the office 365 electron app, but the least work probably ends run a VM and sync off of or just use that. I didn't try wine, so others would have to verify emulation works.
Thanks for the data points!
I'm working on trying to pry local office software copies of outlook from the clutched hands of people stuck in the win 7 era.
Well done sync is a hell of a drug.