Netscreen - Dual-Untrust configuration - need to route email traffic out specific interface

I'm running into an issue here that I am not sure how to fix. After 3 hours of going through the Netscreen ScreenOS manual, I haven't found an answer.

Here is the configuration:

Netscreen 5gt with NetscreenOS 5.3.x

Mode: dual-untrust interfaces.

Ethernet 1 is trust Ethernet 2 is Eschelon t-1 Ethernet 3 is Qwest DSL

Our domain settings point our email DNS at the Qwest DSL, but the default route for the router is to send all traffice including SMTP traffic out the Ethernet 2 (I am assuming because it is the lower numbered interface?)

I MUST have all SMTP traffic send through the Qwest DSL.

I have a policy setup that specifically allows SMTP traffic from the local address of our mail server (10.20.10.21) to out through ANY interface.

I've tried changing the interface by adding an address, but it then bounces to the ANY - ANY profile setup.

Any direction would be helpful.

Thanks!

Jeff