[Mimedefang] Rejecting forged senders - comments?

[Cormack, Ken]

> Something else you can do to cut down on the problem is to make sure 
> Sendmail is set to reject messages with local senders that don't exist. 

We've discussed this, internally.  We host the user mailboxes on internal
Exchange servers, but run MIMEDefang on a pair of machines in the DMZ.  We
could use MIMEDefang's support for querying those servers to see if the
recipient exists or not, rather than relaying the message inbound, only to
have Exchange decide the user doesn't exist.  But that wouldn't contribute
to stopping an email from "me" coming in to "me", for example.  That was the
topic at hand.

Ken