Exchange 2000 Instant Messenger and ISA

[lbicher]

I hope someone can help me out here. I have a Windows 2000 Active Directory domain (service pack 2 on all servers), Exchange 2000 (sp2), ISA 2K Server (SP1) on a member server and Windows XP (sp1) at the desktop. I am trying to get the Exchange Instant Messenging service to work in my environment. I have everything running fine, but only when I am not using the ISA server. Specifically, when I do not tell IE to use the ISA server. Having the Firewall Client on or off makes no difference.
What happens is that there the IM client fails to log on to the Exchange server when IE is set to use the proxy server. When there is no proxy setting in IE, it will log right in. According to my research in Technet, this can happen when authenticating through a proxy server. However, I shoudln't be authenticating through the proxy becase my Exchange servers and my DCs are all on the inside of the proxy. I do have the setting set to bypass local addresses.
So my question is, how do I tell either the client PC or the ISA Server to not have the web proxy service handle authentication when all the services are on the iside of the proxy server?
Thank you all in advance for your assistance.

 

[lbicher]

Hi all,
I have found the answer to my question and wanted to post it in case anybody else is experiencing this problem. As I expected, the problem was that the IM authentication traffic was being passed through the ISA Server, even with "Bypass Local Addresses" option checked. I had thought that IE used the Local Address Table that I set up in ISA to determine what a local address is. I was wrong. The local address is only on the same subnet the client PC is on. Since my server is on a remote subnet, it was going through the ISA server. The fix was to add more address ranges in the Advanced settings button and then everything work the way it is supposed to.