users don't have the information
necessary to set a followup-to email header correctly,
The user simply has to
(1) create a followup field from Reply-To/To/Cc or From/To/Cc, and
(2) remove his address if it's covered by a mailing list.
Exactly which information is he missing?
#1 is trivial to do automatically. #2 is also trivial for MUAs that know
which lists the user is on, such as mutt.
Group-Reply-Pref: exclude-me
This is the Mail-Copies-To approach. It covers many simple situations,
as I mentioned---for example, the default situation described above.
However, I prefer a followup field, for the same reason that I like
having a followup field in news: it's more flexible. For example, I can
manually redirect a crossposted discussion away from an inappropriate
mailing list.
---Dan
Let your users manage their own mailing lists. http://pobox.com/~djb/qmail.html