Usually, I always tell people if you going to handle something that is high load (like emails) of transaction, if possible, implement it as a store-and-forward structure. Basically, one system handle all incoming data and store them temporary. The next system process the data and do the necessary work on them. In this case, there is no need to change your program, just setup the front mail server, and configure such that it will concurrently send 20 (if that is the limit) connections to your anti-spam system.
Just my < 2cents suggestion...
Last edited by ghostdancer; 10-19-2007 at 02:25 AM.