How to Configure Fast Cached Exchange Mode Settings for Outlook 2010 and Outlook 2013 Using Group Policy

Saturday, October 30, 2010
Note: This article and included ADM and REG files have been updated to work with Outlook 2013, as well as Outlook 2010.

Microsoft introduced Cached Exchange Mode in Outlook 2003 and it's been the default configuration ever since.  Cached Exchange Mode saves a copy of your mailbox on your computer which provides quick access to your data and is frequently updated with the Exchange server.

Cached Exchange Mode works like this: When the Exchange Server notifies Outlook of a change, the Download timer starts and Outlook delays receiving the change information.  All notifications that occur in the 30 second window of the Download timer are grouped and processed as a batch at the end of the timer, then the timer is reset.  Uploads to Exchange use a similar Upload timer, which lasts 15 seconds.  For more information, see Description of Outlook 2003 with Cached Exchange Mode in an Exchange Server 2003 environment.  This behavior is the same in Outlook 2007, Outlook 2010, and Outlook 2013.

While this configuration reduces network utilization and load on the target Exchange servers, it reduces the "perceived" performance of Outlook/Exchange.  Users who change from Online Mode to Cached Exchange Mode frequently complain about slow performance, since they're used to the almost "instant messaging" behavior of Online Mode.

This behavior can be changed using a simple registry change, or, as I recommend, using Group Policy.  By changing the Download, Upload, and Maximum timers to one second, your users will enjoy much improved email performance and you will still see improved network performance over traditional MAPI "Online Mode".

 Install the Fast Exchange Cached Mode GPO Administrative Template:
  • Download the CachedMode.adm Group Policy administrative template and save it to a temporary folder.
  • Open the Group Policy Management Console.
  • Navigate to the Default Domain Policy, right-click it, and choose Edit.
  • Navigate to User Configuration > Policies > Administrative Templates.
  • Right-click Administrative Templates and select Add/Remove Templates.
  • Click Add and browse to the location where you downloaded the CachedMode.adm template.  Click OK.
  • The Outlook 2010 Cached Mode Settings administrative template will be added under the heading "Classic Administrative Templates (ADM)".
  • Edit the Outlook 2010 Cached Mode Settings and/or the Outlook 2013 Cached Mode Settings policy and Enable each of the three policies.  I recommend doing both settings - it won't hurt anything.
  • Close the Group Policy Management Console.
The Outlook users will need to download the new group policy and either restart their computer or restart Outlook to get the new settings.

If you are a VPN user or a mobile user who cannot receive Group Policy settings, you can download the FastCachedMode.reg file, and install it manually.  Then close and re-open Outlook to get the new configuration.


  1. Wow! Why hasn't microsoft published this as the official work-around for Outlook 2003/Exchange 2010 upd problems. Holy Cow! You did it!!!!!


  2. link to registry file does not work

  3. Thanks, I fixed the links to download the .reg and .adm files.

  4. This is great, works like a charm. Thanks

  5. Does this work for Outlook 2003, 2007 and 2010?

  6. Great.
    Can you blog about setting the number of days mail, Cached Exchange Mode caches, in E2K13/OLK2K13 ?
    GPO ?


  7. All well and good, but what about the additional load on the Server?

    1. The server load is slightly increased, but it's still MUCH less than using an online MAPI connection.

  8. the standard office 2010 GPO can be used to do this exact step. Setting the values to 1 does seem a little excessive though...


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