[Mailman-Users] basic postfix/mailman setup issue

[Peter]

I am testing a basic installation of mailman 2.1.8 on OpenBSD 4.0.

When I try to reply to the confirmation request I get an error from postfix 
saying that <list>-request at domain.com is not in the recipient table:

Recipient address rejected: User unknown in local recipient table

I thought the mailman aliases handles this?  I have the following in main.cf:

alias_maps = hash:/etc/mail/aliases

/etc/mail/aliases contains:

mailman:              "|/usr/local/lib/mailman/mail/mailman post mailman"
mailman-admin:        "|/usr/local/lib/mailman/mail/mailman admin mailman"
mailman-bounces:      "|/usr/local/lib/mailman/mail/mailman bounces mailman"
mailman-confirm:      "|/usr/local/lib/mailman/mail/mailman confirm mailman"
mailman-join:         "|/usr/local/lib/mailman/mail/mailman join mailman"
mailman-leave:        "|/usr/local/lib/mailman/mail/mailman leave mailman"
mailman-owner:        "|/usr/local/lib/mailman/mail/mailman owner mailman"
mailman-request:      "|/usr/local/lib/mailman/mail/mailman request mailman"
mailman-subscribe:    "|/usr/local/lib/mailman/mail/mailman subscribe mailman"
mailman-unsubscribe:  "|/usr/local/lib/mailman/mail/mailman unsubscribe 
mailman"

What else do I need to do?

TIA,

Pedro