Hello, I do not know if you guys can help me or not. I do not know if you would classify this as an ISA problem, Exchange or IIS. But incase, I am posting the message to IAS list and Exchange List. I am trying to set up Outlook Web Access behind an ISA Server. The Exchange server that I want to talk to is on the same box as the ISA server. It is not the primary exchange server, but it is a member server, I am trying to put together an exchange front end-back end topology. I had followed the recommendation of the documentation that I found to have a DNS A record that would point to the outside address of the ISA server (outlook.company_name.com). I followed the instructions on TechNet to set up a destination set for OWA, and to allow traffic with header destination of outlook.company_name.com to point to the internal web server IP of the ISA/Exchange box. Here is my problem. I think that I am missing something about what is actually going on from an IIS perspective to authenticate to exchange. From inside the network, you type computername/exchange and either the server uses pass through authentication to send you to the right mailbox, or if you do not have a mailbox, then it prompts you for login information. But I cannot tell you how any of the IIS magic happens with Exchange. I do not see any ?default? web page or asp that is executing through the default web site to initiate all of the exchange authentication stuff. I cannot tell if I am dealing with a problem with ISA passing information, or if I am dealing with an IIS issue where all of the right stuff is in the right web space. When I try to hit the DNS name through a web browser, I get every indication that I am having an IIS problem and there is no web page defined or some sort of host header problem. Does any one know what I am talking about or have you dealt with this situation, or implemented a like solution. Thanks in advance, Dwight Maddox Network Administrator Transit Authority, Louisville KY