The first time I looked at Microsoft Exchange Server 5.5 public folders, I thought they would make a great replacement for network file shares that act as document repositories. A second UI to handle messages and documents attracted me, as did the ability to replicate information throughout an enterprise so that a copy was close to users no matter where those users were. Users' ability to create public-folder favorites and add folder shortcuts to the Microsoft Outlook bar also seemed to be useful features.

Exchange 2000 Server's new features only help the case for using public folders. The Web Storage System (WSS) now makes available a URL for any document in a public folder, and Exchange 2000 uses Windows ACLs instead of Exchange Server permissions to control document access. Exchange 2000 supports full-text indexing of mailboxes and public folders. If you elect to generate full-text indexes, Outlook 2000 (or later) clients can use those indexes through Outlook's Advanced Find option—a neat trick that speeds up search operations considerably, especially if your search criterion is a word or phrase that occurs inside the item's body. Exchange 2000 also introduced multiple public-folder hierarchies to replace the single hierarchy that earlier Exchange Server versions used. (This feature's usefulness is difficult to judge, however, because the majority of clients access a single hierarchy. Web clients are an obvious exception, but Outlook Web Access—OWA—isn't the predominant Exchange Server client.) With so many apparent advantages, why use anything other than public folders for document management?

Even with great Web access, integration with Windows 2000 ACLs, improved searching, and multiple hierarchies, Exchange Server public folders provide a flawed document-management solution. No document-reservation functionality exists: Users can't check a document out of a folder to reserve the document for exclusive write access. Therefore, the potential exists for two users to change a document at the same time, especially when multiple folder replicas are available. Additionally, public folders don't support versioning, so you can't revert to an earlier version of a document.

Public folders are a useful tool and serve as acceptable read-only document repositories, but they simply aren't designed to be a document-management system. If you want that type of functionality, look to Microsoft SharePoint Portal Server 2001 or to an add-on Exchange Server product that provides the missing features. (Although the new server operates in the same market as third-party add-on products for Exchange Server, SharePoint Portal Server isn't an attempt to take over the market for Exchange Server­related document-management solutions.