Specify exit interface
I have a pfSense box set with two WAN interfaces.
I have multiple public IP's and have one interface handling x.x.x.242 - x.x.x.244 and one interface handling x.x.x.245 both have the same gateway.
What I want to do is have all SMTP traffic leave out the x.x.x.245 interface.
I would assume that a simple LAN rule would do the job, but since both interfaces have the same gateway, I can't find a way to specify which interface it should exit.
So I'm thinking that I should do this with outbound NAT, but I have tried several things, but none have actually worked. Any ideas how this should be set up?
You don't need and cannot use two interfaces in that way.
Just use multiple Virtual IPs on a single interface, and then you can NAT or do whatever you like.