[mcdan]

The exchange integration ( we use outlook 365 ) for mail works fine, just set it up as IMAP.

The calendar stuff is a bit rockier, but there is project to keep it alive here: https://github.com/ExchangeCalendar/exchangecalendar/

[dwheeler]

I hope that someone will add native Exchange and calendar.

Many organizations do not enable IMAP on Exchange (I know at least one that disabled it). So supporting the native Exchange API would be a big win.

For many people "lack of calendar" means "can't use it".

[weaksauce]

https://addons.mozilla.org/en-us/thunderbird/addon/exquilla-...

seems to be a solution but not free ($10/year/user) and some reviews say that the extension is broken recently.