To me, the ideal solution would be enhanced forum-functionality inside
XWiki. Not only for the this mailinglist (getting all conversation in
one place, linking discussions to the pages/features it concerns) but
for XWiki as a platform too.
I currently have no time to elaborate in a functional proposal, but
roughly: commenting works fine as-is online, but (mail) notification
of replies is lacking (chosing 'watch this page' is unsatisfactory).