Hi I don't know if this is possible but what i want to do is this:

i have an 837 adsl router with 2 public static ip addresses on the dialer interface, I have outbound mail coming from 2 seperate ip addresses on the internal network, i Want to have mail from the first internal ip address to go out via the first external ip address, and mail from the second internal ip address go out via the second external ip address.

I have set up a nat pool that contains both the external ip addresses and i am assuming (hoping) that i just need to setup an access list.