Quoting Timo Sirainen <t...@iki.fi>:
Do you think I'd break a lot of people's filters if I removed the prefix? :) Anyone strongly for/against removing it? It seems kind of annoying to me whenever I happen to think about it.
List-Id has been mentioned as the replacement mechanism by some, but the main issue is that it is not immediately viewable (at least with any rationally configured MUA) to the user. Obviously, filtering by List-Id is the preferred method, since it has the canonical mailing list definition. However, List-Id filtering does not work in all situations.
For example, a common situation (at least for me) is someone who replies directly to your message from a list instead of to the list address. This will most likely cause that message to end up in your INBOX rather than being filtered into the appropriate mailing list mailbox. Having the list name in the Subject can be useful to visually filter these incoming messages in your INBOX, rather than potentially deleting/marking as spam since often times you may not recognize the sender.
FWIW, use of brackets in this manner is sort of a pseudo-standard, insomuch as it is an acceptable component of Subject lines with respect to threading/sorting pursuant to RFC 5256.
michael
