For different versions of Thunderbird, an appropriate add-on must connect to the Exchange server.

• Before Thunderbird 52.0 the add-on Exchange Exchange EWS Provider, last version 3.9.0, was provided by Ericsson. For newer Thunderbird versions this does not work anymore.
• For Thunderbird 52.0 to 52.9.1 you can download and install the add-on Exchange Calendar from GitHub, last version v4.0.0-beta5. Instructions are available on the page.
• Since August 2018 Thunderbird 60.0 is available. Unfortunately the Exchange Calendar add-on does not work in this version anymore, because the further development was stopped by the manufacturer. It remains to be seen whether the Thunderbird community will develop a suitable add-on again. As long as this is not the case, it is recommended to continue using Thunderbird 52.9.1.
  
  We are currently testing the add-on TBSync (to be found via the add-on search in Thunderbird), but can't give a clear recommendation yet.

Instructions for Thunderbird 52.xxx , opens a file in a new window(German only)