How to configure how the Offline Address Book is downloaded when you use Outlook in Cached Exchange Mode


This article describes how to configure how the Offline Address Book is downloaded when you use Microsoft Office Outlook 2003, Microsoft Office Outlook 2007, Microsoft Outlook 2010, or Microsoft Outlook 2013 in Cached Exchange Mode.

More Information

To configure how the Offline Address Book is downloaded when you use Outlook in Cached Exchange Mode, follow these steps to configure the DownloadOAB value in the Registry.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
  1. Click Start, and then click
  2. In the Open box, type
    regedit, and then click OK.
  3. Locate and then click to select the following key:

    Outlook 2003



    Outlook 2007



    Outlook 2010



    Outlook 2013



  4. In the Edit menu, point to New, and then click Key.
  5. Type Cached Mode.
  6. On the Edit menu, point to
    New, and then click DWORD Value.
  7. Type DownloadOAB, and then click
  8. In the right pane, right-click DownloadOAB, and then click
  9. In the Edit DWORD Value dialog box, type the value that you want, and then click OK.
  10. On the Registry menu, click Exit.
You can set the DownloadOAB value to any one of the following values, depending on your situation:
  • 0 = The Offline Address Book does not download automatically.
  • 1 = The Offline Address Book uses the Download Full Items download mode. This is the default setting.
  • 2 = Download the Offline Address Book in any download mode, but download a differential update in the Header only download mode.
  • 3 = Always download the Offline Address Book and a differential update in one of the following download modes:
    • Download Headers and then Full Items
    • Download Full Items 
    • Download Headers 

When you set this registry value to 0 (zero), cached-mode Outlook is forced to perform directory lookups against an Active Directory directory service global catalog server. This action increases the timeliness of access to modified or new Active Directory objects. However, this action also negates some of the increased tolerance for network latencies and outages.

Important Note: If Offline Address Book (.oab) files were previously downloaded and associated with a MAPI profile for Microsoft Outlook, this setting will not have the correct effect. To use this setting, you must set the registry value, remove any .oab files from the local computer, and then synchronize.

The location of the .oab files on your computer vary according to your Outlook version and the version of Windows on which Outlook is installed. The default location for .oab files is provided below.
  • Outlook 2010 and Outlook 2013
    • Windows 7 or Windows 8

      %userprofile%\AppData\Local\Microsoft\Outlook\Offline Address Books\< guid >
    • Windows XP (Outlook 2010 only)

      %userprofile%\Local Settings\application data\Microsoft\Outlook\Offline Address Books\< guid >

      NOTE: < guid > in the above folder path varies between Exchange organizations. The folder name, for example, will look like 0a1f33a0-dbeb-4007-92e3-57926c848000
  • Outlook 2007 and Outlook 2003
    • Windows 7 or Windows 8

    • Windows XP

      %userprofile%\LocalSettings\application data\Microsoft\Outlook

Article ID: 823580 - Last Review: Aug 22, 2012 - Revision: 1