Superb Rated 5 out of 5 stars

ThunderBrowse 3.8 in one word: superbly done (oops, make that TWO words!)

This download point works: https://addons.mozilla.org/en-US/thunderbird/addon/thunderbrowse/versions/

This review is for a previous version of the add-on (3.3.5).  This user has other reviews of this add-on.