As I talked about in a previous post, a common solution for companies running Exchange is to use redirection to dump all incoming user request to the OWA sub directory on the CAS server. HTTP to HTTPS redirection is also commonly implemented. Recently I found a gotcha to this configuration. When a user connected with Outlook Anywhere does a Send/Receive, it will hang on the Offline Address Book, sometimes permanently until either the task is cancelled or Outlook is restarted.
After a long while of troubleshooting this issue, I finally lucked on to the answer when I did a browse to the OAB.xml file on port 80 from the console in IIS and received a 500 error. After digging around for the reason I was locked out, I finally found why.
When you enable redirection with the HTTP redirection feature in IIS 7, it places a web.config file in every sub directory of the default web site. This is the reason you have to go disable redirection on all the sub directories after turning it on at the DWS. For some reason, the web.config file in the OAB subdirectory was the only one that authenticated users did not have read access to. To fix the issue, I granted authenticated users read rights to the web.config file.
Note: The OAB subdirectory is located at
C:\Program Files\Microsoft\Exchange Server\Client Access\OAB