Applies to: Exchange Server 2010 Topic Last Modified: 2009-11-11

You can use the Shell to disable Web beacons and HTML forms on Outlook Web App. A Web beacon is a file object, such as a transparent graphic or an image, that's put on a Web site or in an e-mail message. Web beacons are typically used together with HTML cookies to monitor user behavior on a Web site or to validate a recipient's e-mail address when an e-mail message that contains a Web beacon is opened. Web beacons and HTML forms can also contain harmful code and can be used to circumvent e-mail filters.

By default, Web beacons and HTML forms are set to UserFilterChoice. This blocks all Web beacons and HTML forms but lets the user unblock them on individual messages. An administrator can use the Shell to change the type of filtering that's used for Web beacon and HTML form content in Outlook Web App.

Web beacon configuration is set on a per virtual directory basis for each Outlook Web App virtual directory in your organization.

For more information about Web beacons, see Managing Outlook Web App Advanced Features.

Looking for other advanced management tasks for Outlook Web App? Check out Managing Outlook Web App Advanced Features.

 Use the Shell to block Web beacons and HTML forms in Outlook Web App

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Outlook Web App virtual directories" entry in the Client Access Permissions topic.

This example blocks all Web beacon and HTML form content on an Outlook Web App virtual directory named Owa in the default Internet Information Services (IIS) Web site on the local server.

Set-OwaVirtualDirectory -identity "Owa (Default Web Site)" -FilterWebBeaconsAndHtmlForms ForceFilter

The possible values for FilterWebBeaconsandHtmlforms are as follows:

• UserFilterChoice   By default, this value blocks Web beacons and HTML forms, but lets the user allow Web beacons and HTML forms on individual messages.
  
• ForceFilter   This value blocks all Web beacons and HTML forms.
  
• DisableFilter   This value allows Web beacons and HTML forms.
  

Note:
Both UserFilterChoice and ForceFilter give the user an option to unblock blocked content on individual messages. If the parameter has been set to ForceFilter, the content will remain blocked regardless of the user's choice.

For more information about syntax and parameters, see Set-OwaVirtualDirectory.