An HTML attachment of a shared mailbox cannot be saved when you set the "BypassOwaHTMLAttachmentFiltering" setting to "True" in an Exchange Server 2007 environment

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Article ID: 2394731 - View products that this article applies to.
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Consider the following scenario:
  • You have a user mailbox and a shared mailbox in a Microsoft Exchange Server 2007 environment.
  • The user mailbox has Full Access permission to the shared mailbox.  
  • You set the BypassOwaHTMLAttachmentFiltering setting to True in the Web.Config file.

    Note The Web.Config file is located under the following path:

    <drive>\Program Files\Microsoft\Exchange Server\ClientAccess\Owa
  • You send an email message that includes an HTML attachment to the shared mailbox.
  • You log on to the user mailbox by using Outlook Web Access (OWA). 
  • You select "Open Other Mailbox", and then open the shared mailbox.  
  • You open the email message, and then try to save the HTML attachment. 
In this scenario, you cannot save the HTML attachment. Additionally, you receive an error message that resembles the following:

Error :  IE cannot download attachment.ashx from localhost. The file could not be written to the cache.

Note If you set the BypassOwaHTMLAttachmentFiltering setting to False in the Web.Config file, this issue does not occur.


To resolve this problem, install the following update rollup:
2407025 Description of Update Rollup 2 for Exchange Server 2007 Service Pack 3


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


The BypassOwaHTMLAttachmentFiltering setting is introduced since Update Rollup 8 for Exchange Server 2007 Service Pack 1. For more information, click the following article number to view the article in the Microsoft Knowledge Base:  
958881 All HTML content in attachment files of messages is run through an HTML filter when you open or save the attachment by using Outlook Web Access (OWA)


Article ID: 2394731 - Last Review: December 14, 2010 - Revision: 1.0
  • Microsoft Exchange Server 2007 Service Pack 3, when used with:
    • Microsoft Exchange Server 2007 Enterprise Edition
    • Microsoft Exchange Server 2007 Standard Edition
kbqfe kbfix kbsurveynew kbexpertiseinter kbhotfixrollup KB2394731

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