Eliminating Public Interface

[jrost]

I currently have a BM server that host primarily File sharing and groupwise. I have BM installed on the server and we access groupwise webaccess, SMTP, IMAP and POP via the public interface. I want to eliminate the public interface and route all traffic through our 3rd party firewall and take this server off of the internet. However when I disable the public interface and change the default route none of the services are working. I have narrowed it down to the tcpip filters. What is the best practice for eliminating this interface and making sure all traffic routes through the private interface. I do not have any of the BM modules loaded and really dont use any of the services but I think what happens is traffic comes in through the private but it is still trying to route through the public interface.