I took the opportunity of the slow season to make some changes to the mail server configuration: it's moved to another server and the mailing lists are now driven by mailman3 (before: mailman2) with hyperkitty as mailing list archive system (before: pipermail).
I'm still importing and otherwise handling the archives, but the mailing list should work now. For you, I hope that the only impact will be that mailman3 has a new user management concept that manages users on a per-server basis and not per mailing list like mailman2 did. This means that your mailman credentials are void and you'll have to request new ones.
If you notice anything odd with the mailing list, I'd appreciate a heads-up.