Locating Free/Busy Information for Other Users

When a user schedules an appointment or meeting and wants to determine the availability of another user, the client must obtain free/busy data for that user. To do this, the client must first locate the appropriate free/busy folder, and then identify the free/busy message for the specified user. Outlook performs this task slightly differently than Outlook Web Access and Outlook Mobile Access.

Locating Free/Busy Information with Outlook

When locating a user's free/busy public folder, Outlook uses a process that is similar to its publishing process. Outlook starts by retrieving the user's legacyExchangeDN value from Active Directory, and then uses that value to identify the name of the free/busy folder and the subject line of the appropriate free/busy message. Outlook then searches for the appropriate folder and message, starting with the specified user's default public folder store, and if necessary, requesting a referral to an appropriate server.

Locating Free/Busy Information with Outlook Web Access or Outlook Mobile Access

When Outlook Web Access or Outlook Mobile Access requests free/busy information for a selected user, the Exchange server that supports the Outlook Web Access applications (generally a front-end server) processes the request. The front-end server sends a query to the users default public folder store, which responds with a list of available free/busy servers. As is the case with a normal public folder referral, the front-end server sends a query to the first available server in the list, which responds with the free/busy data. The front-end server only queries another free/busy server if the first server in the list does not respond. If Outlook Web Access or Outlook Mobile Access does not use a front-end server, the users default public folder store will only respond with a single free/busy server. If that server is unavailable, the request will fail. No other servers can be queried.