Microsoft Exchange Server objects are instances of MAPI COM classes, or just MAPI objects. A MAPI object is an instance of a COM class that implements one or more MAPI interfaces.
object identifier (OID)
A value specifying the nature of an X.400 object. OIDs are used by MAPI for various purposes, such as indicating the types of attached files.
offline folders
A feature of Microsoft Exchange Server that makes public folders and mailbox folders available to users when they are offline. Folders configured for offline availability are stored in an OST file on the user's disk. When users log on to their home server and the network connection is reestablished, Microsoft Exchange Server automatically propagates changes that have been made to the offline copy to the copy on the server.
offline folder store (OST)
An information store that is used to store folder information that can be accessed offline. An OST is similar to a PST except that it is RTF aware, while a PST is not.
one-off address
Address of a foreign system as expressed by an address template.
operational attribute
A directory schema attribute that is used by the directory service itself or other services of Microsoft Exchange Server.
organization
A collection of servers, grouped into sites, that are linked together to provide workgroup connectivity, information, and messaging services. The organization is the highest level object in the directory information tree (DIT).
organization forms library
A programming interface that stores electronic forms for use by an entire organization. The forms library architecture is defined by MAPI. It functions independently of any specific forms technology and can store forms from multiple forms-development environments. It resides in the public information store as a hidden public folder and is replicated throughout the organization for user access to forms.