Import of http://bugs.musicbrainz.org/ticket/1613
Copying the description. Some ideas for fixing it are on the comments on Trac. Currently only notes to an edit by the same editor are threaded on Gmail, but you get one mail for each editor that posts.
I use GMail, and I got used to a very nice feature: all replies to an email are grouped under what GMail calls a "conversation". I won't describe it in detail, anyone can check on GMail how it works.
Anyway, this works very well for discussions on the mailing lists, but for some reason it doesn't work for mod notes, despite the fact that they have the same subject.
I'd very much like it if it worked