When you edit a message in a replicated public folder, the PFRA for that information store updates the state information for that message. It then sends a replication message containing the modified message and its attachments to the other information stores that maintain replicas. The list of information stores that maintain these replicas is a property of the folder.
When an information store receives a new replication message, the new message replaces the existing message on the local computer only if the original message modification was made to the same version or a later version of the existing message ¾ that is, if the new message is more current than the existing message.
Which message contains the most recent information is determined by the change number and the predecessor change list. If the change number of the existing message is included in the predecessor change list of the new message, the new message replaces the existing message.
The following illustration shows how replication occurs when there are no conflicts.