If you add a user to more than one group, when Outlook starts it finds and uses the most recently created item that contains that user. Outlook does not retrieve all of the items from the folder, and Outlook does not evaluate all of the permissions that the user has been granted over the folder's history. Therefore, it is important that you carefully plan the security settings groups and which users are members of each group. When a user starts Outlook, Outlook checks to see if a registry key is set and configured to use custom security settings. If it is, Outlook retrieves the user's settings from the Outlook Security Settings public folder.
Outlook looks for custom administrative settings.
The behavior that is described may seem different from the behavior that is described in section 2.4 of the Readme.txt file. The Readme.txt file implies that if you have no key or if the key has a value of zero, Outlook checks for settings on the server. Section 2.4 of the Readme.txt file provides details about how to deploy the registry to the user's computers. The method that you use to deploy the registry varies depending on configuration and whether or not policies are in effect. How to Manually Create the Registry Key For information about how to create the registry key, see section 2.4.3 of the Readme.txt file.