This is because Microsoft Exchange Server 2003 and earlier versions publish user free/busy information in the SCHEDULE+ FREE BUSY dedicated public folder. The SCHEDULE+ FREE BUSY folder is available to any authenticated user. However, Exchange Server 2007 introduced the Availability Service. The Exchange Availability Service allows for access to be configured per user and to control how much free/busy information is shared. If a user does not configure free/busy information to be shared, you cannot use Open Other User's Folder to view their free/busy information.
Note Outlook 2007 and newer versions retrieve free/busy information from the Availability Service when the mailboxes are on Exchange Server 2007 or later versions.
For more information about the Exchange Availability Service, visit the following Microsoft TechNet website:
To use Open Other User's Folder, follow these steps:
- Start Outlook.
- On the File menu, point to Open, and then click Other User's Folder.
- In the Open Other User's Folder dialog box and then type the name of the user who owns the folder in the Name box.
- Change Folder type to Calendar and then click OK.