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As an IT consultant, I work with different Exchange organizations. To keep my messages and addresses on my laptop PC, I configured Outlook to synchronize to an offline folder (.ost file) and the Offline Address Book (OAB). I created a separate directory for each organization and specified a different path for my offline folder. The only problem was that by default, the OAB synchronizes to the same location for all profiles and overwrites the previous OAB.

Looking closer, I figured out that versions earlier than Outlook 2000 usually store the OAB in the Windows systems directory—\windows\ system32, where windows stands for your windows directory (e.g., \winnt)). Outlook 2000 stores the OAB at \windows\Profiles\ Profilename\Local Settings\Application Data\ Microsoft\ Outlook by default. However, you can't modify the OAB path with Outlook's GUI.

To create a separate OAB for each profile, I modified the Registry to set the OAB path on a profile's level. First, back up the Registry before you make changes to it. Then, activate the offline use option for the profile. From the menu bar, go to Tools, Services and select Microsoft Exchange Server. Click Properties, and select Enable offline use on the Advanced tab. You can also configure this parameter from the Mail and Fax applet in Control Panel.

If you've synchronized the OAB with an Outlook version earlier than Outlook 2000, the OAB path already exists as a Registry string value. If you've never synchronized the OAB before or are using Outlook 2000, you must create the Registry key manually. Start regedt32 from the command line, and go to HKEY_CURRENT_USER\Software\ Microsoft\ Windows NT\ CurrentVersion\Windows Messaging Sub\system\ Profiles\ MyProfile\ 13dbb0 c8aa05101a9bb000aa002fc45a, where MyProfile is the profile name. The Profiles key holds all the profiles installed for the current user. If the string value 001e660e exists under 13db b0c8aa05101a9 bb000aa002fc45a in the right pane, open it and enter a valid directory path as data where you want to store the OAB in the file system. If this string value is missing, create it from the Edit menu and use 001e660e as the value name. The value data must contain a valid target OAB directory path.