Keeping the "deepest" message Rated 5 out of 5 stars
I really like this add-on, and seems extremely fast as long as the message body is not included.
I just wanted to add to the "keep deepest" message. It does seem that when one sorts by folder, a shallower folder will always precede a deeper folder. However, it would be great to get a confirmation of this, since then one could be quite confident that sorting by folders and keeping the last message would result in keeping all the painstakingly sorted messages one has, and deleting the ones that one has redownloaded into the inbox.
Please file such requests in the mozdev.org bugzilla: http://www.mozdev.org/bugs/