A search folder provides a means of querying for items that match certain criteria. To the user, a search folder appears in the client as a normal folder that populates itself when opened. A search folder uses one of the standard templates or a custom search created by the user to include specific search criteria.
This protocol enables a client to persist a user's search folders on the server, thereby allowing the user to access these folders when connecting via a client on another machine. The client maintains search folders within a mailbox by using search folder definition messages. To create a search folder, the client collects the data that is used to define the search criteria, creates a search folder container to contain the results of the search, and creates a search folder definition message to persist the information that defines the search folder. This information includes the search criteria. A search folder definition message is saved as a folder associated information (FAI) message in a hidden folder outside the root mailbox and is not directly visible to the user.