MTA Trusted Networks

I am trying to migrate from Desknow to Zimbra as the later seems to be more featured but the MTA issue is driving me nuts.

I am not an expert at Linux by any means so I am doing everything from the Admin console.

I am getting the "...must contain local network interfaces..." error.

I am also using Webmin which lets me see all the network interfaces but still no luck.

Only complicating item is that I have IPv6 installed and running on my LAn so the Zimbra box automatically picks up an addr.

This is probably very simple but I am not seeing it.

Any help would be appreciated.

That mean:
-MTA trusted networks must has itself: such as 127.0.0.1/32 or your mail server address with subnet mask is 32 (255.255.255.255) or the ip range that has your mail server
-All machines these are placed in trusted network can send mail with out passing authenticate step