I have an ActionTec MI424-WR router that has 5 external IP addresses bound to it.
One of the servers behind the router is a mail server on an internal address. When the mail server receives mail, it is responding on x.x.x.52. Which the router correctly port forwards to the internal machine.
However, when it sends mail, it is doing so on x.x.x.50. There are two problems with this. First, the .50 address is listed in a spam database (It was that way when the IP was assigned to me). Second, .50 isn't my mail server so I don't have a reverse DNS pointer set up for it. I do for the .52 address.
What I need is for my mail server to use the .52 address when it sends traffic out.