Review for FolderFlags by w_d_p
Rated 5 out of 5 stars
Top notch!
Since I had a "Junk" and a "Bulk" folder after I set up a yahoo account in Thunderbird, I deleted the "Bulk" one which seems to have caused a lot of problems. It appeared in the Trash folder over and over again .... With this Add-On I was able to get it out of the Trash folder .... See also https://www.reddit.com/r/Thunderbird/comments/xdfqub/junk_bulk_folder_in_trash_yahoo_mail/
To create your own collections, you must have a Mozilla Add-ons account.