Does anybody know anything about Mailman?

I upgraded my server to Debian Lenny the other day, and everything seemed ok until this morning. I evidently spammed myself with the couple of hundred VERPed bounce messsages that normally Mailman is supposed to silently handle. Instead, they seemed to have all ended up in my inbox, and there is no indication in /var/log/mailman/bounce.1 that Mailman even saw them.

I’ve checked that postfix still has the mail delimiter set to +, and if I send out a message to a VERP style address on my box it does get delivered. It even appears that the bounces got delivered to “/var/lib/mailman/mail/mailman bounces mailman”. I just can’t understand why they then got delivered to me – normally Mailman does whatever it does and doesn’t bother me about them.