My lists have implemented a filter for quite a while that for the most
part enforces the list policy of not including more than relevant
portions of a prior post. Every message on the list has a helpful
trailer tacked on about what list it is from, how to unsubscribe, etc.
If a post to the list is recieved with this trailer anywhere in it, the
post is bounced back to the sender. This mechanism also functions to
prevent many of the mail looping problems that have occurred.
Thus, for the common case of a user not editing out anything, messages
are rejected. If they make any effort at all to edit the message, they
usually have the sense to cut it down to the relevant parts. The only
noted side effect is that when people ask about how to unsubscribe, the
replies that say "hey you #%^(ing blind bat, didn't you see this tag at
the end of every #%*@ing message?" get rejected as well.
So if you can put in a piece of known text into the body of all messages
(in the headers doesn't help for includes), you can have your list filter
(you DO have a list filter, right??) reject messages with this text in it.
This alone will do wonders for cutting down on included text AND protect
you from most mail loops.
-- James Lick -- email@example.com -- http://drivel.com/jlick/ --