I believe mailman 2 as used on lists.gnu.org is the backend we care about here. I would prefer it if the mailing list Web frontend would work as a MUA producing messages that look good in plain text, monospace e-mail clients. The MBOX from selected GNU mailman lists would be the “forum” threads prominently displayed; other mail would be private messages. Should every user be given a @guile-forum.gnu.org mail address?
Regards, Florian