I am having a problem with bot Yahoo instant messenger and Microsoft Exchange Instant Messenger. I can't get them to go through the ISA, I am using the Firewall Client but that doesn't let them through. I have tried about every proxy setting --http, socks4, socks5. I believe my problem lies in the fact that I am requiring authentication for all outgoing web requests so that I can monitor who is going where. When I turn this on, people can't get authenticated through the proxy. Not sure, any help would be appreciated.