Surprisingly good is a stretch. Barley adequate more like it.

Now that they've hidden mail access behind oauth (imap and SMTP, additionally SMTP behind global default off policy) and graph api behind oauth2 - it looks like they don't have to worry about real mail clients competing.

Actually fighting [f] to get mail in/out working with freescout right now - and having had learn more than I care to about o365 and PowerShell etc - I wonder how hard it would be to write a couple of stand alone tools to get fetch/send/sync mail working with o365 and local maildir - to get my/sup/any sane Mua to really work with o365/exchange/outlook.

Then there's calendar and teams to deal with..

[f] Thankfully our o365 reseller does most of the fighting - I'm happy to not have tenant-wide admin in AD/entra/whatever kerberized LDAP is called today.

Correction - not "my" but "mu" (mail utils):

https://www.djcbsoftware.nl/code/mu/

Btw, anyone still reading/participating mailing lists? From MacOS? Have you found a reasonable client?

I'm not even going to try with Outlook.