I second that.
Often ppl on the list will (b)cc: users@spamassassin.apache.org, so we need something like a [listserv name] subject header.
If you can find anything not covered in past threads, feel free to repost, but please read the archives first. There's a rather obscenely large number of posts on this subject there.
Might I suggest a few choice posts for your convenience:
http://article.gmane.org/gmane.mail.spam.spamassassin.general/40690/match=subject+prefix
http://article.gmane.org/gmane.mail.spam.spamassassin.general/40735/match=subject+prefix+new+list
Or any search of the gmane archives for:
subject prefix new list
subject tag poll results