I work for a company that is located in an area where the fastest Internet connection available is 3M/512K DSL. Due to growth of Internet use we now have configured (4) DSL connections in our SonicWall TZ-210 router using "Ratio" load balancing.
In order to make this setup work I had to configure a route so that all outbound email goes out on port X1, our original DSL connection. Without this routing we frequently get return failures. Our X1 DSL connection is the one that has SPF and PTR records configured. It's also the IP address to which our MX record is forwarded.
Looking at the reports in the SonicWall I can see that this X1 connection is by far the busiest, not to mention that our server (SBS 2008, our only server) is sending and receiving some 90% of all Internet traffic. Is there some way that I can allow our server to send out emails on any of our DSL connections/IP Addresses? Do I just need to setup PTR records (reverse DNS) for each of our DSL connections/IP Addresses?