Using Zimbra as a smart Host

[jrefl5]

I'm trying to get my Zimbra 5.0.9 NE to RELAY mail sent from some internal servers on to external e-mail accounts. I have set the sending servers in my "MTA Trusted Networks" via zmprov modifyserver command;

zmprov modifyserver ServerName zimbraMtaMyNetworks '127.0.0.0/8 10.168.30.60/32 10.168.30.5/32 ...

but when the sending server (using sendmail) sends an e-mail destined to external destination we get ;

Action: failed
Status: 5.7.1
Remote-MTA: DNS; zimbra-server.com
Diagnostic-Code: SMTP; 554 5.7.1 <SomeTestAcc@gmail.com>: Relay access denied
Last-Attempt-Date: Wed, 12 Nov 2008 13:34:01 -0700

What am i missing?

[jrefl5]

I can see the e-mail hitting the zimbra server in zimbra.log, but it appears to be entering from the Firewall's address, not the sending servers IP