This past week the AT&T Internet Service Provider has changed policies regarding mail relaying through their network.

I need help configuring Zimbra to authenticate with the AT&T mail relay (I have to use their mail relay in order to send out SMTP email over the Internet).

Since Zimbra doesn't have any place in the Admin GUI for login credentials to the AT&T mail relay, I know I need to hit the command line...

I know at least someone using Zimbra is using AT&T's DSL ISP network and must have already figured this out...

Please Help!