Applies to: Exchange 2010 SP3
You set hideDLMembership attribute to true of a distribution list (DL) in order to hide distribution list’s members from users. But users are still able to list the members of the DL
On taskbar, right bottom, ctrl+right click on outlook icon, click connection status.
You see that Problem user’s Outlook client directly connects to Global Catalog (GC) server for Exchange Directory service instead of Exchange 2010 Client Access Server (CAS).
On non-Problem user you can see that Outlook is connected to Exchange 2010 CAS Server for Exchange Directory Service service.
On the client PC, DS Server registry is set to a certain GC for forcing Outlook to use specific GC
(How to configure Outlook to a specific global catalog server or to the closest global catalog server
1- On the problem PC, close Outlook
2- Click Start, and then click Run.
3- In the Open box, type regedit.exe, and then click OK.
find DS Server key under
4- Delete DS Server key.
5- Start Outlook
Current Outlook versions no longer directly connect GC anymore by default. Outlook connects Exchange 2010 CAS Server’ NSPI interface for directory requests, CAS server connects to GC and returns the results to Outlook client.