Rated 3 out of 5 stars

This restores a useful feature that was annoyingly removed from Thunderbird (though I still miss the parenthetical unread message number, which takes less space than a column). As others have pointed out, this extension does NOT work properly with the "Smart Folders" view (inbox accounts are all listed as "Inbox" instead of the account names. Ditto for Sent, Drafts, and Trash). Hopefully that'll be addressed in a future version.

This review is for a previous version of the add-on (0.4).