We've got a number of aliases in our (old) mail system that we're migrating away from, where you might have

USER@mydomain.com ---> USER@department.mydomain.com

Because "Department" has decided to run their own mail system completely independent of us. It also happens when we have things like:

LISTNAME@mydomain.com ---> LISTNAME@mailman.mydomain.com

Where can I set up "system" aliases.... aliases that don't belong to specific users, but which are forwarded along to the proper "offsite" address?

Also, we've got some where it's

assistants@mydomain.com --> a@mydomain.com, b@mydomain.com

It's not really used as a "distribution list", but more in terms of "so either a or b can act on it depending on who is less busy". Not looking for the overhead of a "distribution list", but is there any way to do multiple recipients per alias?

Thanks much!