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How to enforce Microsoft Outlook cached mode via group policy

Users can easily disable Exchange cached mode, since Outlook does not require any special permissions to do so. However, you can enforce cached mode at the group policy level.

Normally, you can enable Exchange Server cached mode support when you install Microsoft Outlook on users' machines....

Unfortunately, they can easily disable it, since Outlook doesn't require users any special permissions to do so. However, you can enforce cached mode at the group policy level.


The group policies I explain in this tip are only effective for Outlook 2003 clients. Furthermore, many of the group policy settings are only effective for new Microsoft Outlook profiles.

Microsoft Outlook group policy administrative template

Windows does not include Outlook-related group policy objects by default. So before we get started, you have to download an administrative template and import it into your effective group policy.

You can download a a self-extracting file that contains administrative templates for all the various Microsoft Office applications (Word, Excel, etc.). To enforce cached mode though, you only need the Microsoft Outlook template, OUTLK11.ADM.

Once you've downloaded the template, you need to import it:

  1. Open the Group Policy Editor and navigate to User Configuration -> Administrative Templates.
  2. Right click on the Administrative Templates container and select Add/Remove Templates.
  3. Click the Add button and you will be prompted for the template you wish to import.
  4. Select the OUTLK11.ADM file from the folder where you extracted the various Microsoft Office administrative templates, and click Open, then Close.

The template is now imported into the Group Policy Editor.

Setting up the cached mode group policy

  1. To access the portion of the Microsoft Outlook group policy administrative template that affects Exchange cached mode, navigate through the Group Policy Editor to User Configuration -> Administrative Templates -> Microsoft Office -> Outlook 2003 -> Tools -> E-Mail Accounts -> Cached Exchange Mode.

    When you select the Cached Exchange Mode container, the console's Details pane will display about a dozen group policy objects related to cached mode. The good news is that you don't have to touch most of these. (The majority of the cached mode group policy objects relate to disabling cached mode or disallowing the caching of full messages and/or message headers.)

  2. To require users to use cached mode, double click the Cached Exchange Mode (File -> Cached Exchange Mode) option and select Enable.
  3. There is also a dropdown list from which you can select what data should be cached. I recommend selecting the Download Full Items option.

An extra group policy for mobile users

If you have mobile users in your organization, another handy group policy object is the Disallow on Slow Connections setting. If you enable this option, Microsoft Outlook will test the speed of its connection to Exchange Server. If it perceives a slow connection, only message headers will be downloaded rather than the entire message.

Outlook performs a speed test because just checking the rate of the computer's network adapter is not a reliable measurement of speed. For example, suppose a computer had a 10 Mbps network adapter connected to an ISDN modem. The network adapter would report that communications were flowing at 10 Mbps.

In actuality, communications would only be moving at 10 Mbps between the NIC and the ISDN modem. Communications between the ISDN modem and remote host, on the other hand, would flow at a maximum of 128 Kbps. If Outlook didn't perform its own speed test, it would never know that the connection was slow.

About the author: Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Exchange Server, and has previously received Microsoft's MVP award for Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. As a freelance technical writer, Brien has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal Web site at

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