You’ll need to install two add-ons:
- Lightning — install this via Tools/Add-ons in Thunderbird
- Exchange EWS Provider — download the .xpi file from here: https://github.com/Ericsson/exchangecalendar/releases, then go to Tools/Add-ons, click the cog-wheel in the upper right corner, next to the search box, and select “Install Add-on from file”
Now to go to Events and Tasks/Calendar in Thunderbird, go to File/New/Calendar, pick On the Network, Next. Pick Microsoft Exchange, Next. Call it whatever you want, and pick the email address associated with it (your UMU email).
Selected Hosted Exchange, Use Exchange’s autodiscovery function, and click Perform autodiscovery. Select https://webmail.ad.umu.se/EWS/Exchange.asmx
Put your CAS ID (along the lines of abcd01234) in the Username box, and click on Check Server and Mailbox
Then click Next. Done!