This update only applies to Exchange Server 2003 clusters running on Windows Server 2003 with the recently released Windows 2003 sp1. MS KB 841561 fixes "'500 - Internal server error' error message when a user tries to access a clustered Exchange Server 2003 back-end server by using Outlook Web Access."
|•||If a user tries to access a mailbox by using Microsoft Outlook Web Access, that user receives the following error message:|
|•||If you log on to a client computer by using administrator rights and then try to access a mailbox by using Outlook Web Access, you are successful.|
In this scenario, when a user tries to access a mailbox by using Outlook Web Access, HTTP requests into the clustering API by impersonating the logged-on user. However, there have been security changes in Windows Server 2003 SP1. The security restrictions for the APIs that perform remote registry access have been changed. Therefore, the logon attempt is not successful.