Offline Address Book (oab) Settings

One of the common issues that I have seen for Outlook users is that the offline address book in their local machine is out of date. This may cause the user can not find a new contact in the address book, or send mail to the outdated email address.

The simplest way to solve the problem is to close the Outlook, then delete all *.oab files under the following folder.

For Win XP: %USERPROFILE%\Local Settings\Application Data\Microsoft\Outlook\
For Win 7: %USERPROFILE%\AppData\Local\Microsoft\Outlook\

If you want to control the download setting of the offline address book, you need to play some tricks in the registry.

Copy the following highlighted texts into a reg file, and change the value of DownloadOAB depending on your situation, then import the reg file.

Outlook 2003:
Windows Registry Editor Version 5.00[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Cached Mode]
“DownloadOAB”=dword:00000000

Outlook 2007:
Windows Registry Editor Version 5.00[HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Cached Mode]
“DownloadOAB”=dword:00000000

Outlook 2010:
Windows Registry Editor Version 5.00[HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Cached Mode]
“DownloadOAB”=dword:00000000

• 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