I'm beginning to think this is impossible! :-)
I've been doing some Google searching about the file local-host-names, one hit suggested trying the following to see what sendmail views as local domains:-
echo '$=w' | sendmail -bt
... and what does it return ....
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked) Enter <ruleset> <address> > home home.isbd.net localhost [192.168.1.1] isbd.net
Which certainly looks as if sendmail thinks that home.isbd.net is the local machine. However when I tried using 'mail' to send a message from root to chris@home.isbd.net (I used 'mail' to ensure little else was involved) it *still* tries to send it out to the outside world.
The entries in maillog are:-
Nov 11 11:38:20 home sendmail[7883]: lABBcJ9h007883: from=root, size=64, class=0, nrcpts=1, msgid=200711111138.lABBcJ9h007883@home.isbd.net, relay=root@localhost Nov 11 11:38:20 home sendmail[7884]: lABBcKac007884: from=root@home.isbd.net, size=354, class=0, nrcpts=1, msgid=200711111138.lABBcJ9h007883@home.isbd.net, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1] Nov 11 11:38:20 home sendmail[7883]: lABBcJ9h007883: to=chris@home.isbd.net, ctladdr=root (0/0), delay=00:00:01, xdelay=00:00:00, mailer=relay, pri=30064, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (lABBcKac007884 Message accepted for delivery) Nov 11 11:40:20 home sendmail[7886]: lABBcKac007884: to=chris@84-45-228-40.no-dns-yet.enta.net, delay=00:02:00, xdelay=00:02:00, mailer=esmtp, pri=120354, relay=84-45-228-40.no-dns-yet.enta.net. [84.45.228.40], dsn=4.0.0, stat=Deferred: Connection timed out with 84-45-228-40.no-dns-yet.enta.net.