Rated 5 out of 5 stars

This is an extremely useful tool for anybody who has thousands of emails to search through. Unfortunately, it is not compatible with newer Thunderbird releases.

To use this tool:
Click Tools - Options - Config Editor
Click "I accept the risk"
Search for "update.enabled"
Change value to False

Exit out of Thunderbird
Uninstall Tunderbird using Add-Remove programs
Install Thunderbird version 60.0
archive.mozilla.org/pub/thunderbird/releases/60.0/win64/en-US/

After all that is done, you should then be able to install and use the add-on.