For Users who are using Terminal Service or Remote Desktop.
(Multiple users of a computer using Outlook Messenger at the same time)

How to:
1. Exit Outlook Messenger if it is already running.
2. Install the Terminal Service Tool in the computer by logging in as Administrator or a member of the Administrator group. Use the Terminal Service Status tool to make sure the Terminal Service Tool is running.
3. Run Outlook Messenger and in Settings > Network Tab, enable the Terminal Service Tool option. Re-Start Outlook Messenger.
4. Repeat step 3, for each user who logs in to the computer using Terminal Service.