You are the messaging engineer for your company. Your network contains one Microsoft Exchange Server 2003 server named Server1 and one Exchange Server 2007 server named Server2. Server2 hosts the Mailbox server role, the Client Access server role, the Hub Transport server role, a mailbox database, and a public folder database. Users access e-mail and free/busy information by using Microsoft Office Outlook 2003, Microsoft Office Outlook 2007, and Outlook Web Access clients.

You plan to move mailboxes from Server1 to Server2. When the move is complete, Server1 will be removed from the network. You need to recommend a solution that ensures all users are able to access the free/busy calendaring functions after their mailboxes have been moved to Server2. What should you recommend?