How can I allow the MSN Messenger to connect through our ISA Caching Only Server. Ideally we would like to allow certain machines, depending on Group membership to use MSN Messenger through the ISA server. Defining the proxy on port 80 in the MSN Mesenger does not seem to be enough and I cannot create a specific protocol definition on port 1863 in Caching Only mode. I do not want to setup the ISA server as an integrated server since we rely on our Cisco PIX for firewall functionality and we want to keep it that way....for now ;-)) TIA, Peter