I thought that hypperkitty is just a web page to search the mailing lists...
You can reply right in there, too -- so it's pretty much a forum -- assuming the threading works.
Sadly several threads were broken and it doesn't seem reliable.
In contrast , CentOS forum is much more usable.
Sadly, it is quite broken at the moment. We have a ticket open, and there is an upstream bug filed with the mailman team. We're now waiting on our ovirt infra person (Duck) to reply to run some debugging commands and get back to them.