I only described the technical back-drop for mailing lists. The behaviors of setting Reply-To: headers, and of rejecting posts from non-subscribers, are still implemented as hacks against the old mechanism. These configuration features have not changed how mailing lists work.

My original original point is that moderating mailing lists is not possible. I have not seen an effective counterargument. Reply-to munging and subscribe-to-post do not add up to effective moderation, and are easily circumvented.

I have seen it happen: someone banned from posting to a mailing list harassing discussion participants anyway. Perhaps he subscribed with a phony e-mail address to collect the list traffic, and then just composed replies as himself to everyone in the debate, but excluding the list robot (which would reject the copy).

"Modern" mailing lists still pass through the Cc: material which makes this possible, even though they set Reply-To, and disallow posts from non-members.

I don't care how you set up your mailing list; you're not going to easily be able to moderate out persistent trolls. You can't use IP block banning easily, because trolls don't contact your server directly; they can go through any number of e-mail service providers. If a troll keeps coming back over and over again, using different gmail addresses, are you going to ban everything from gmail?