The Microsoft Exchange Server implementation of a MAPI message store is called an information store.You will use MAPI functions and methods to work with information stores.
A Microsoft Exchange Server information store can contain messages, forms, documents, and other information created by users and applications. It provides each user with a server-based mailbox and stores public folder contents.
In addition, the information store enforces security, replicates public folders, enforces storage limits, and delivers messages to users on the same server. It maintains information in two databases: the public information store and the private information store. For information about the structures and characteristics of information stores, see About the Information Store.