Unfortunately this is not possible unless Wikimedia maintains its own mailman package and modifies the source code as that page is generated via Python and not a single html template as the example pointed out.

See http://bazaar.launchpad.net/~mailman-coders/mailman/2.1/view/head:/Mailman/Cgi/listinfo.py for the source code of that page.

Also that is un compiled. In order to change it, be auses it is pure Python - you'll need to rewrite that part of mailman, compile it and then convince an op to put it on apt.wm.o and so on. In sort - it is possible but not preferred and likely won't have people (especially ops) gunning for it. Better to wait the while for mailman 3 to get into upstream and have a coordinated plan to upgrade or that - which has a nice design because it wasn't written pre 2000!

It's possible to hide lists from that already, but that's not an improvement.

• everything John already said, the HTML templates don't really help because it's Python

• there is already https://meta.wikimedia.org/wiki/Mailing_lists/Overview which can be edited sooo much easier by anyone

• there is no real defintion of "inactive" ("by default" would mean you have some kind of objective criteria what inactive means), but if it is really inactive a list admin can easily hide it from that overview with a single mouse click.

• re: hiding / separating "private" lists. What exactly does "private" mean here? Did you mean that it's hidden from the listinfo overview? Or that not everybody can subscribe witout being confirmed? That the archives are private? All of the above? Also, we have policies that say we do NOT want to hide the mere existence of lists.