Postfix not relaying correctly

[Plight]

Hello. I have the following issue:

I am using postfix to notify on certain script failures. It is running on a machine with 2 nics, each on a separate network (lan and wan). On the lan side is our exchange server which postfix relays to. When both nics are up, it relays fine. When the lan nic is taken down, postfix no longer relays correctly and starts listing something along the lines of:

sendmail[2690]: o5MHHU5A002690: from=user, size=205, class=0, nrcpts=1, msgid=<201006221717.o5MHHU5A002690>, relay=root<at>localhost

sendmail[2690]: o5MHHU5A002690: to=user, delay=00:00:00, mailer=esmtp, pri=30205, dsn=4.4.3, stat=queued

relay=root<at>localhost changes depending on the user, so it looks like it is relaying local instead of using my relay.

I can still ping and access the exchange server via telnet on the same ip and port 25 so its not a firewall issue. It looks like a routing issue but nothing has changed aside from a network card being disconnected.

thanks.

[scathefire]

is it safe to assume that cron calling the script?

if so, are you using a personal crontab or the /etc/crontab?

if you use /etc/crontab do you have MAILTO set to something specific (like root)

if so, have you editted your /etc/aliases folder to point your internal domain?
e.g.

root         admin@yourdomain.com

but remember, it will need a DNS server to resolve your domain.

or you may just have to set your exchange server as the smart host inside of postfix, if you haven't all ready