There's no need for an IMAP extension; there's already tags, but Thunderbird is pretty much the only mail agent that has some kind of support for IMAP tags. Goo

There's no need for an IMAP extension; there's already tags, but Thunderbird is pretty much the only mail agent that has some kind of support for IMAP tags. Google uses the folder hack in part because support for tags is so bad. However it would be nice if Google supported both folders and tags.