Welcome to Thunderbird Add-ons.
Add extra features and styles to make Thunderbird your own.Close
Make usable for later versions Rated 5 out of 5 stars
Save the .xpi (right-click Add to Firefox -> Save as -> open using winrar, or the like -> extract install.rdf -> edit using notepad or equivalent for your OS -> find <em:maxVersion> -> change to *.* -> add back to .xpi using winrar -> install
It works for me.