I know your experience seems to contradict this, but
cron/mailpasswds only mails to current subscribers.
Did you really mean lists/list-name/config.db file? Since
Mailman 2.1, the list config/membership is in
lists/list-name/config.pck. If you have config.db files,
they shouldn't be coming into play at all in Mailman 2.1.x
(except in initial upgrade when they are used to create the
Are the users possibly subscribed to some old, inactive
version of the list?
In any case, I don't think that a user who is not a current
subscriber to 'list@domain' can receive a password reminder
for 'list@domain' from 'mailman-owner@domain'.