I wish to setup a local mail server for debugging purposes using fedora 15 I set up sendmail, but there is a problem.

When I'm not connected to the internet, the local mail server delivers correctly (to localhost). And in /var/log/mail I see that I correctly delivered a mail to [email protected]:

Jun 21 18:24:56 PowersourceII sendmail[6019]: p5LGOttt006019: [email protected], size=328, class=0, nrcpts=1, msgid=<[email protected]>, relay=adriano@localhost
Jun 21 18:24:56 PowersourceII sendmail[6020]: p5LGOuSV006020: from=<[email protected]>, size=506, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=PowersourceII.localdomain [127.0.0.1]
Jun 21 18:24:56 PowersourceII sendmail[6019]: p5LGOttt006019: [email protected], [email protected] (500/500), delay=00:00:01, xdelay=00:00:00, mailer=relay, pri=30328, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (p5LGOuSV006020 Message accepted for delivery)

When I connect, networkmanager fills in /etc/resolv.conf with:

domain fastwebnet.it
search fastwebnet.it localdomain
nameserver 62.101.93.101
nameserver 83.103.25.250

Now sendmail does not work any longer and tries to send messages to my ISP domain, as seen in the log:

Jun 21 18:40:02 PowersourceII sendmail[6348]: p5LGe1LV006348: [email protected], [email protected] (500/500), delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=30327, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (p5LGe10n006352 Message accepted for delivery)
Jun 21 18:40:02 PowersourceII sendmail[6354]: p5LGe10n006352: to=<[email protected]>, delay=00:00:01, xdelay=00:00:00, mailer=esmtp, pri=120651, relay=mx3.fastwebnet.it. [85.18.95.21], dsn=5.1.1, stat=User unknown

As you can see, it tries to deliver a mail to [email protected], and fails

The setup is working under other ISPs. How can I avoid the fastweb ISP DNS relay? Thank you