If you would like to use the previous version of Shift (3.9.1), you can download it using one of the following links.
Make sure you use the correct download link for the Operating System that you are using.
Make sure you first quit Shift, then download the fresh copy from one of the links above.
If you are not on the Stable channel, please make sure you change your channel to Stable in your Shift settings prior to downloading one of the links above.
Using this older version of Shift will let you continue to use MailTrack and Collabspot like the previous version of Shift.