upgrade of postfix broke Mailman

[Kevin Coyner <kevin@rustybear.com>]

On a box running Sid, I recently apt-get dist-upgrade'd Postfix.  Prior
to the upgrade I had Postfix running smoothly with a virtual setup based
on MySQL tables.  Additionally, I had Mailman integrated into
everything.

After the upgrade, I first found that virtual users no longer received
email.  I fixed this quickly by adding to main.cf:

local_recipient_maps  =  $virtual_mailbox_maps

with $virtual_mailbox_maps representing all of my users with email
addresses.

But in adding this, I found that attempts to deliver to Mailman no
longer got through (got a 550 error saying "User unknown in local
recipient table").

So I removed it again and presto, Mailman delivers properly.  

So with 'local_recipient_maps' I can deliver to my virtual users but not
to Mailman.  And without 'local_recipient_maps' I cannot deliver to
virtual users but can deliver to Mailman.

How do I reconcile this?

In the upgrade the dynamicmaps.cf file was changed, and 'proxy' was
added to master.cf.  On the surface I don't see how these changes could
have screwed me up, but perhaps I missing something.

I've got a thick book on Postfix, but it hasn't helped on this one.  And
I've gooogled til my eyes have started spinning.

Any help would sure be appreciated.

Thanks
Kevin