A private information store is the MAPI message store implementation (part of the Microsoft Exchange Server information store) that stores mailboxes for users. Once you have a handle to a MAPI session, you can use it to locate the private information store for the user whose profile you used to log on.
For more information on obtaining a session handle, see Opening an Information Store. For examples of using the HrOpenExchangePrivateStore function, see the sample application source files \BKOFFICE\SAMPLES\EXCHANGE\MBLSAMPL\MBLSAMPL.C and \BKOFFICE\SAMPLES\EXCHANGE\MBXSERV\MBXSERV.CPP.