You follow the Microsoft Knowledge Base (KB) 958881 article to configure the BypassOwaHtmlAttachmentFiltering option on a Microsoft Exchange Server 2007 server. However, you still cannot save some attachments successfully by using Outlook Web Access (OWA). Those affected attachments are saved as empty. This problem occurs when the attachments contains HTML content. However, the file name extensions of the attachments are not .html or .htm.
To resolve this issue, install the following update rollup:
2407025 Description of Update Rollup 2 for Exchange Server 2007 Service Pack 3
After you apply this fix and set the BypassOwaHTMLAttachmentFiltering option to True, you have to set the file name extensions of the HTML attachments in the Force Savelist. To do this, follow these steps:
In the Exchange Management Console, click Server Configuration, and then click Client Access.
In the action pane, under Outlook Web Access, click Properties.
Click either the Public Computer File Access tab or the Private Computer File Access tab.
Under Direct file access, select the check box next to Enable direct file access to enable users to download attachments.
Click Customize next to Customize direct file access to change the type of attachments that you want users to be able to access.
On the Direct File Access Settings page, click Force Save. Then, set the .xls file name extensions in the Enter the file extensions you want to force save, one at a time dialog box on the Force Save List page, and then click Add.
Click OK three times to save your settings.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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)