Note: this feature was removed from Outlook 2003 and above.

In certain configurations, Microsoft Outlook can expose data in the Contacts folder to the Windows Address Book (WAB) that Outlook Express uses. In effect, this means that Outlook and Outlook Express are sharing the contacts. Creating a new contact in the WAB actually creates a new contact in the Outlook Contacts folder.

Note that if you turn on sharing between Outlook and OE, any data previously entered in the Outlook Express address book will not be visible until you turn off sharing. You must choose whether you want to see Outlook contacts or the original OE address book. You can't have both.

Outlook 2002 and Outlook 2000 CW | Outlook 98 and Outlook 2000 IMO | More Information

Outlook 2003, Outlook 2002 and Outlook 2000 CW

Officially, Outlook 2002/2003 and Outlook 2000 in Corporate/Workgroup mode do not support sharing of its contact data with Outlook Express, but there is a registry hack that works, at least with some versions of Outlook Express. Follow these steps:

1. Make a backup of your Windows registry.
2. Open the Registry Editor (regedit.exe or regedt32.exe).
3. Go to this registry key:

HKEY_CURRENT_USER\Software\Microsoft\WAB\WAB4\

4. Add a new DWORD named UseOutlook (if it isn't already present), and set its value to 1.

Outlook Express will display the Contacts folder in the default delivery store (Exchange mailbox or Personal Folders .pst file) in Outlook. You cannot direct the WAB to a particular Contacts folder, except by changing the default store.

To turn off sharing, set the value for

HKEY_CURRENT_USER\Software\Microsoft\WAB\WAB4\
DWORD: UseOutlook 
Value: 0

This is a valid registry entry for Outlook Express 5.0 and later versions. Outlook MVPs have tested it with Outlook 2003, Outlook 2002, and Outlook 2000 CW and OE 5.0 and 6.0 so far. Thanks to MVP Frank Saunders for pointing it out.

Note that this technique shares only contacts. Outlook Express cannot read information about Outlook distribution lists that might be stored in the Contacts folder.

Also note that when you use Outlook Express you'll see Outlook.exe running in Task Manager even if you don't have Outlook open.

Outlook 98 and Outlook 2000 IMO

If you are using Outlook 98 or Outlook 2000 in Internet Mail Only (IMO) mode, you can set Outlook Express to display Outlook's Contacts folder in the Windows Address Book. See:

• OL2000- (IMO) How Do I Share Information Between Outlook and OE
• OL98- (IMO) How Do I Share Information Between Outlook and OE (Q179505)
• OL98- (IMO) Option to Share Contacts with Outlook Not Available in Windows Address Book