[lug] postfix domain alias?

[Rob Nagler]

We've got a strange situation to deal with.  Rackspace is hosting an
exchange server for one of our clients, and they have configured a
"split domain" in a strange way.  We are hosting foo.org, and they are
hosting foox.org.  The users accessing the exchange server are logging
in with joe at foox.org, and sending mail to our servers list at foo.org.
However, the exchange server wants to hide foox.org so it is rewriting
joe at foox.org to joe at foo.org, which our server knows how to forward
back to the exchange server.  All well and good.

The problem is that for some unfathomable reason exchange is
converting the recipient from list at foo.org to list at foox.org.
foox.org's MX record points to the exchange server, not our servers,
but our servers are being sent the recipient list at foox.org.
Postfix is looking up list at foox.org, and sending it back to the
exchange server.

I want to trick Postfix into delivering list at foox.org as a local
address.  foox.org is in Postfix's mydestination list.

One alternative is to create foox.org virtual aliases for all the
mailboxes we handle, but that's a maintenance nightmare -- lists can
be created/deleted dynamically.

You can do this with sendmail, but I can't figure out how to do this
with Postfix.

Thanks,
Rob