Hello,
I have had a big problem with Mailman yesterday and today: two or three hours after I sent out my "big list" message (150 000 subscribers), Mailman started to spend all its time using CPU, for ages. In fact, it was the bounce runner that had started to send out the "probe" messages, one by one, making VirginRunner lock the list repeatedly, and holding the lock for 15s each time. Meanwhile the web admin interface was unreachable (for that list), and other scripts waited and failed.
I finally looked everywhere to find out what was happening, and cleaned up the qfiles/virgin/ queue of all the probes, and waited another two hours for the qflies/command/ queue to empty... not very good.
As I have a very big server (4 CPUs, 6Gbytes of RAM), I suppose that only a MySQL-backed Mailman would answer this problem. How far is it from being usable?
-- Fil