We have a local mail server with mail forwarding set up in sendmail.cf (sendmail version 8.13.7+Sun) to send e-mail out of our local network (intranet) to a set of mail servers on the internet.
The problem with this is that ALL LOCAL e-mail is also going to the internet mail servers instead of being routed directly by our local mail server. In other words, when host x.a.b.c sends to host y.a.b.c his mail goes first to the local mail hub ... then up to the internet facing mail servers ... then back into our local network (domain a.b.c) and is finally routed to the destination. We would rather see the local mail server recognize that y.a.b.c is local and just send the e-mail directly to that host.
We understand that there is way to inhibit mail forwarding for hosts in the local domain in sendmail.cf but we find the documentation cryptic. Can someone help?