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Part 1: An overview of the Exchange public folder replication process

Get a general overview of how the Exchange public folder replication process works through the use of the Exchange Information Store service and Active Directory.

Exchange Server uses a multi-master replication model for replicating public folder content. What this means is that all copies of an Exchange public folder are treated equally. There is no master copy of a public folder. If a user makes a change to a public folder's contents, it does not matter which copy of the folder the change was made to. The change will be detected and synchronized with all other copies of the public folder. In Microsoft-speak, these public folder copies are referred to as replicas.

The Exchange Information Store service controls replication related to the public folder hierarchy (the public folder tree), and the content of each folder. For the purpose of this tutorial, "content" refers to message headers, message bodies, and any attachments that might exist.

Although the replication process is automated, and is controlled by the Microsoft Exchange Information Store service, it is still the administrator's responsibility to set up the destination and frequency of the replication.

When the Exchange Information Store service detects that a change has been made to a public folder replica, it must synchronize that change to the other replicas in the organization.

Believe it or not, the synchronization process is email-based. Replication-related email messages are sent from one Exchange server to another using the exact same protocols and connectors that any other email message would use.

There is one important difference between replication email and regular email though: Exchange Server treats replication-related email as system messages. This means that replication messages are not bound by the same limitations as normal email. For example, content, size and delivery restrictions that apply to normal email do not apply to system messages.

Although the Exchange Information Store service is the primary mechanism used for public folder replication, it is not the only mechanism at work. Active Directory uses a replication method of its own to keep domain controllers synchronized with each other. This replication occurs at the Windows operating system level and is completely independent of Exchange Server. Active Directory replication occurs even if Exchange Server is not installed on the forest.

Although Active Directory replication works outside of Exchange Server, Exchange Server does make use of this process when it comes to replicating mail-enabled public folder directory objects. These objects are replicated to domain controllers and global catalog servers in exactly the same way that user accounts are replicated.


 Home: Introduction
 Part 1: An overview of the Exchange public folder replication process
 Part 2: The Exchange public folder replication methodology explained
 Part 3: What content should you replicate in Exchange public folders?
 Part 4: How to create Exchange public folder replicas
 Part 5: Related resources on Exchange public folder management

Brien M. Posey, MCSE
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Exchange Server, and has previously received Microsoft's MVP award for Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. As a freelance technical writer, Brien has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal Web site at

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