Sendmail as a relay gateway
I am quite new to Linux and have a question about setting up relay rules in Sendmail:
We have an external SMTP gateway with postfix that forwards all our incoming mail to our Exchange server.
Now we have installed a Spam gateway with Mailscanner, Fedora 7 and sendmail that filters out spam before it reaches the Exchange server.
So the external gateway is now sending all incoming mails to this gateway.
All of that works fine with the relay to our Exchange server.
Now I want to activate the Watermark function in Mailscanner to get rid of all those NDR mails. To be able to do that I must relay all outgoing mail from the Exchange server through the Mailscanner-Fedora-Sendmail gateway.
So I must create a relay rule in sendmail that says: relay all mails for domain [mydomain.com] to the internal Exchange server and all other domains to our external gateway.
I have only accomplished the first part and have had no luck with the outgoing mail flow.
I'm sure the solution is easy so I hope for a quick answer!