My proposal can be implemented (for example) as a `copy me on replies'
toggle in the user interface.
That would work with all of the proposals here. You claim that it is an
advantage of your proposal; you are wrong.
Your proposal requires the UA to identify addresses that are mailing lists
and include them in the Reply-Destinations (or whatever you call it) field.
Wrong. The correct algorithm is as follows. If the MUA knows that the
user has subscribed to a mailing list shown in To+Cc, it automatically
excludes him from subsequent followups. Otherwise it leaves him in.
This, too, would work with all of the proposals here.
Let your users manage their own mailing lists. http://pobox.com/~djb/qmail.html