What I would like to do is similar, but, just a single host IP:port (the pfsense LAN interface address actually) to an internal LAN host:port (port being the same for both).
What I am trying to do is have LAN:25 (and ONLY LAN:25) being redirected to the internal:25. All other WAN destinations:25 would be unimpeded.
I have tried a LAN NAT rules with the "external" source the LAN interface IP and any port to the internal IP port 25. But, as you might guess, it only works when you are on the pfsense shell such that you are coming from LAN interface IP. I am sure there is some way to do this. Maybe it takes more than one NAT rule to do. Not sure.