I have a single Exchange 2003 server. I just recently added a new Exchange 2007 server. I've got just about everything up and running and have migrated a couple test mailboxes from 2003 to 2007. All users are using Outlook 2007.
The issue: users that now have mailboxes on the Exchange 2007 server (mailboxes that were migrated from the 2003 server) cannot view the Free/Busy info for any of the users whos mailboxes are still on Exchange 2003. They can view the Free/Busy info for the other users who have been moved to 2007 server. Both servers are in the same Exchange Org. All mailflow is working fine. The users whos mailboxes are still on the Exchange 2003 server CAN view Free/Busy info for all users on both servers.
If a user with a mailbox on 2007 opens Outlook they can view the calendars of other users on 2003, however if they try to create a new calendar event and use the Scheduling Assistant, the information for the 2003 user will not be displayed, it just says "no free/busy information could be retrieved"
Since we have many users I need this to work so that I can phase the migration from 2003 to 2007. Please help.