You try to download a .zip file attachment in Microsoft Outlook Web Access (OWA) from a server that is running Microsoft Internet Security and Acceleration (ISA) Server 2004 Service Pack 2 (SP2). However, you cannot download the .zip file attachment as expected. Additionally, you receive the following error message:
500 Internal Server Error. Not implemented (-2147467263)
This problem occurs because OWA uses the "Content-Encoding: none" HTTP header when it sends .zip file attachments. After you install SP2 on ISA Server 2004, ISA Server rejects this request to download the .zip file attachment.
To resolve this problem, obtain the update for HTTP issues in ISA Server 2004 SP2. For more information about this update, click the following article number to view the article in the Microsoft Knowledge Base:
916106 Update for HTTP issues in Microsoft Internet Security and Acceleration Server 2004 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the terminology that is used to describe Microsoft software updates, click the following article numbers to view the articles in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates