Most attributes in the Microsoft Exchange Server directory can be accessed as MAPI properties. For example, where you might use the directory access function DAPIRead to export the Surname attribute of a Mailbox directory object, you could also call IMAPIProp::GetProps to find out the PR_SURNAME property of the same object.
Directory attributes are divided into two groups: attributes on the various types of recipient objects and attributes on nonrecipient objects. For more information on recipient attributes, see About Recipient Attributes. For more information on nonrecipient attributes, see About Nonrecipient Attributes. Each of these sections contains a table that maps directory attribute names to MAPI property tags.