Exchange Server public folders are intended to serve as a repository for information that is shared among many users. Public folders should be used when your business requires data replication to multiple servers. Access to public folders is integrated with regular mailbox access through the following protocols:

• Microsoft Office Outlook® 2003 (MAPI clients)
  
• Clients that are compatible with Internet Message Access Protocol (IMAP), such as Outlook Express
  
• Microsoft Office Outlook Web Access (Web client)
  

Offline access to public folder content is available through the Favorites public folder in Outlook.

Note:

Consider the following two issues before you use the Favorites public folder in Outlook. First, the Favorites public folder allows users to add public folders that they use frequently to a central location in Outlook. When users add a public folder to their Favorites public folder, the content of that public folder can be configured to periodically synchronize for offline access. Such synchronization increases network load. The second issue that you should consider is a common mistake that users commit when they remove items from a public folder in their Favorites folder. Users frequently delete messages and posts that they have read in a public folder in their Favorites folder, just as they would delete e-mail items in their other Outlook folders. When Outlook synchronizes with the Exchange Server public folder, the messages in the public folder are also deleted. Frequently, users do not expect or anticipate this behavior.

Public folders are generally used for the following purposes:

• Public folders can be used for shared communication, such as discussions through message posts, shared e-mail messages, contacts, group calendars, archiving of distribution list posts, and support for Network News Transfer Protocol (NNTP).
  
• Public folders can be used for shared content management. Like file shares, public folders can be used to store content, such as documentation. Public folders are also good for sharing content if you do not require versioning and provisioning.
  

If you require offline storage of information or replicated storage of information, public folders are an ideal repository.

However, public folders were not designed for the following functions:

• Public folders were not designed for archiving data. Users who have mailbox limits sometimes use public folders, instead of personal folder (.pst) files, to archive data. This practice is not a recommended best practice because it increases storage on public folder servers and undermines the goal of mailbox limits.
  
• Public folders were not designed for document sharing and collaboration. Public folders do not provide versioning or other document management features, such as controlled check-in and check-out functionality, and automatic notifications of content changes.
  

As a document sharing and collaboration solution, SharePoint Products and Technologies offer the following advantages over Exchange Server public folders:

• You can use SharePoint Products and Technologies for document management. SharePoint Products and Technologies provide version control with controlled check-in and check-out functionality.
  
• You can use SharePoint Products and Technologies to provide browser-based client support for collaborative features. Users gain access to these collaborative features through Office Outlook Web Access.
  
• You can use SharePoint Products and Technologies to provide automatic notification of content changes.
  

  Note:
  This functionality requires an SMTP server.

• You can use SharePoint Products and Technologies to create Meeting Workspace sites from Outlook 2003.
  
• You can use SharePoint Products and Technologies to integrate with Office applications, such as Microsoft Office Live Communications Server 2003 for instant messaging and presence information. Presence is the status, such as online, away, or busy, that is displayed by your instant messaging program when you pause on your contact's icon.
  
• You can use SharePoint Products and Technologies to administer portals and sites.
  
• You can use SharePoint Products and Technologies to link a document library to a public folder in Exchange 2000 Server or later versions to a SharePoint site.
  
• You can enable cross-site searches by setting up Office SharePoint Portal Server to search indexed public folders and other shared databases.
  

However, you should consider possible limitations to SharePoint Products and Technologies when you compare SharePoint Products and Technologies and Exchange Server.

For example, SharePoint Portal Server is not mail-enabled, although you can develop your own solution to mail-enable SharePoint Portal Server. Exchange Server public folders can be mail-enabled so that users and applications can submit posts by using SMTP or MAPI.

Additionally, SharePoint Portal Server does not support replication. Therefore, if you use SharePoint Portal Server, carefully consider how you will deploy data stores when you plan for current and future regional use.

Finally, SharePoint Portal Server does not integrate with Outlook so that users can manage documents. The default Exchange Server MAPI public folder stores are automatically displayed in Outlook after you install. This automatic display allows users to post through the Outlook user interface.

One last element to consider when you compare SharePoint Products and Technologies and Exchange Server is your migration path from Exchange Server public folders to SharePoint Portal Server. Currently, Microsoft has not released any tools that enable easy migration of data from public folders to the SharePoint Portal Server architecture.

To learn more about public folders in Exchange Server, see the following resources:

• Best Practices for Exchange Server Public Folders
  
• Selecting the Appropriate Client for Exchange Public Folder Access
  
• Exchange Public Folder Best Practices: Implementing Replication
  
• Exchange Public Folder Best Practices: Understanding Referrals
  
• Exchange Public Folder Best Practices: Mail-Enabling Public Folders
  
• Exchange Public Folder Best Practices: Managing Data
  
• Exchange Public Folder Best Practices: Scalability
  
• Exchange Public Folder Troubleshooting Resources