Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

Exchange Server 2010 users cannot open certain attachments when they access their mailboxes by using Outlook Web App

View products that this article applies to.


In a Microsoft Exchange Server 2010 environment, you have Microsoft Internet Security & Acceleration Server (ISA) 2006 SP1 installed. Exchange Server 2010 users access their mailboxes through the ISA server by using Microsoft Outlook Web App (OWA) together with Windows Internet Explorer. However, the users cannot open certain attachments. Additionally, the following error is generated:

Internet Explorer cannot download ...spid=xxxx from
Internet Explorer was not able to open this Internet site. The requested site is either unavailable or cannot be found. Please try again later.

If the users directly access the Exchange Server 2010 CAS server by using OWA, they can open these attachments.
Note The file types that are affected include .doc, .pdf, and .xls.

↑ Back to the top


Exchange Server 2010 OWA adds a "Content-Encoding: none" string to a response and ISA 2006 SP1 adds a �Vary: Accept-Encoding" string to the response. The combination of the string in the response prevents Internet Explorer from caching the files.. Therefore, Exchange Server 2010 users cannot open the attachments by using OWA.

↑ Back to the top


To resolve this problem, install the following update rollup:
976573� Description of Update Rollup 1 for Exchange Server 2010

↑ Back to the top

More information

For more information about headers for the Vary field, visit the following Microsoft Web site:

↑ Back to the top

Keywords: KB977439, kbqfe, kbfix, kbexpertiseinter, kbsurveynew, kbhotfixrollup

↑ Back to the top

Article Info
Article ID : 977439
Revision : 2
Created on : 2/8/2010
Published on : 2/8/2010
Exists online : False
Views : 373