do you mean in
isaserver/servers and arrays/server01/access policy/ip packet filters?
if so, i did. it allows 1863 outbound, and still, messnger says "Logon to MSN Messenger Service failed because the service is not responding. The service is not avaliable or you may not be connected to the Internet."
This message has been one of two shown, the other being something like "the proxy server declined your request"
:-(