This tip applies only to BCM version 1. Version 2 (released July 2005) supports all versions of Exchange server.
As many users of Exchange and Outlook 2003 discovered, Business Contact Manager is not available when you have an Exchange mailbox in your account, as explained in this KB article: KB 829748. The normal workaround is using two different profiles, one for BCM and one for Exchange.
Microsoft has an update available which allows BCM to work with a Small Business Servers Exchange account. You can find the details of the patch and links to the patch here: KB 831747. To use this patch you need to use SBSs Exchange server and use cached mode in Outlook.
Using this registry key puts you into an unsupported mode.
Enable cached mode if its not already enabled and close Outlook.
Install the SBS patch then add the following key to your registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\smallbusinessserver\clientsetup String name: Version Data Value: 5.2
If you don't want to edit the registry yourself, use this ready to use registry key to make the change:
SBS registry key
While I don't expect non-SBS users will have problems using this fix, keep in mind this is unsupported. This means if you have problems with Outlook or BCM when using this key with non-SBS Exchange server accounts, don't call Microsoft's Product Support looking for help until after you remove the key and verify the problem still exists.