Public folders aren't designed for the following purposes: In Exchange Server 2010, public folders are an optional feature.If all client computers in your organization are running Microsoft Outlook 2010 or Office Outlook 2007, there are no dependencies on public folders for features such as free and busy information and offline address book (OAB) downloads.After that, all public folder databases are optional.
Instead of using public folders for OAB downloads and free and busy information, in Exchange 2010, these features are serviced by the Autodiscover service, the Microsoft Exchange System Attendant service, and the Microsoft Exchange File Distribution service.
Until all client computers in your organization are running Outlook 2010 or Outlook 2007, you should continue using public folders.
For more information about how to create a public folder database, see Create a Public Folder Database.
Public folders, introduced in the first version of Microsoft Exchange, are designed for shared access and provide an easy and effective way to collect, organize, and share information with other people in your workgroup or organization.
Public folders are hierarchically organized, stored in dedicated databases, and can be replicated between servers running Exchange.
If the answer is yes, a public folder database is created.
If the answer is no, a public folder database isn't created.
Contents Computers running Outlook 2003 and earlier or Microsoft Entourage require a public folder database (previously called the public folder store) to connect to Exchange.
Therefore, in a pure Exchange 2010 organization, as you install the Mailbox server role on the first server, Setup prompts you with the question: Do you have any client computers running Outlook 2003 and earlier or Entourage in your organization?