Running Sendmail 8.12.10 on a Redhat Linux 9.0 Enterprise machine. This server sits in a DMZ. Its hostname is "ns1priv" in the local domain "priv.local". We have masqueraded the domain so that outgoing mail shows as "email@example.com". Now we need to have this box accept all mail for "domain.com" and route it to an Exchange server that sits on the inside network.
At this point, testing mail sent from the Internet to "firstname.lastname@example.org" returns a "user unknown" message as the user doesn't exist on the localhost.
How can we configure Sendmail to pass all the mail that is for our "domain.com" into the Exchange server? Without becoming an open relay, of course.