Hello All,I have a running test Exchange 2003 server in the perimeter network (DMZ zone). Same box is running both Domain Controller and Exchange. On the staff subnet (non DMZ), OWA is working fine but Outlook clients are failing. I have enabled RPC over HTTP by installing RPC over HTTP proxy service on the server. I even tried configuring Outlook profile to use RPC . Outlook is asking for user name and apssword now to make connection to my mailbox on server but then failing after few seconds with error saying "Exchnage Server is unavailable". Same username and password works in OWA but now in outlook. Server is using Basic Aurthentication for RPC and so is the client.Please suggest what is wrong.Thanks,Gigs

The Steps to enabling RPC/HTTP in Exchange 2003: 1. Install RPC Proxy Service 2. Specify the Exchange Server as part of an RPC/HTTP environment in ESM, Administrative Groups > Servers > Server Properties > RPC 3. Install a PKI certificate on the RPC/HTTP Server, this should preferably be a public trusted cert but internal CA works fine too. Note: outlook will NOT connect using RPC/HTTP if ssl is not enabled. 4. Edit the RPC ProxyRegistry Stringon the RPC/HTTP server according to the following article: http://thelazyadmin.com/index.php?/archives/39-Configure-RPC-over-HTTPS-Exchange-Server.html 5. Allow connections on Port 443 (SSL) to the RPC Proxy on your firewall 6. configure Outlook for RPC/HTTP