Exchange has an API that could be used for syncronising. I always wanted to build this into vdirsyncer [1] (so that I can use khal with my work Office 365 account) but haven't found the time.
I use Davmail to talk to O365 and present standard interfaces like imap/caldav/smtp/etc and then use vdirsyncer to pull down my work calender to use with khal. It works pretty good for me, especially now that Davmail does MFA internally so no account changes are needed in O365
interesting, thanks for the information, I'll give that a go.
Interesting. Does DavMail support creating new calendar events or modifying existing ones and syncing them back to Office 365?