SharePoint 2007: Outlook Integration and Forms authentication

To enable Outlook Integration in SharePoint 2007 extended Forms authentication based Extranet web site: Set RememberMeSet to true in login page asp:Login control.

This will set an expiring cookie and will be stored in the end-users system enabling outlook to access the user sharepoint credentials (cookie).

Note:
Please be sure to enable client integration in
Central Administration
Application Management
Authentication Providers (Select your application )
Select Extranet Zone
Check Client Integration and Click Save.

Note:
To synchronize SharePoint lists to Outlook, please look at stssync (http://msdn2.microsoft.com/en-us/library/ms868667.aspx).