D

deferred action: The deferral of an action when a rule is applied because a resource (typically the client) is unavailable. Deferred action processing consists of collecting and storing these actions until the resource becomes available, at which time the action is performed.
deferred action message (DAM): A message that indicates an action has been requested by a rule, but the action cannot be performed because the resource (usually the client) is not available. This message is received by the affected resource when it becomes available. Reception of the message triggers the action that was deferred.
delegate access: Access to another user’s mailbox that is assigned by the owner of the mailbox. Delegate access can be of several types, such as create and send messages or read-only.
delivery report (DR): A report sent to the originator of a message when the message is successfully delivered to one of its intended recipients.
directory: A Microsoft Exchange Server component that serves as the central repository of user information and Microsoft Exchange Server information for an organization. The directory for Microsoft Exchange Server consists of the directory information tree (DIT) and the directory schema.
directory access functions: A set of functions included with the Microsoft Exchange Server SDK that are used to manage information in the directory. Directory access functions are typically used for managing objects when creating and maintaining custom add-on services, managing a large number of directory objects at one time, synchronizing Microsoft Exchange Server directory objects with other directory services, and automatically updating Windows NT user accounts as directory objects are updated.
directory exchange agent (DXA): A Microsoft Exchange Server component that handles the transfer of directory information between the Microsoft Exchange Server directory and foreign mail systems such as Microsoft Mail 3.2 post offices. It also maintains synchronization between these objects.
directory information tree (DIT): A graphical display of an organization’s directory structure, sites, and servers, shown as a branching structure. The top-level (root) directory usually represents the organization level.
directory replication: The copying of a master set of directories from an export server to specified servers in the same or other domains. Replication simplifies the task of maintaining identical sets of directories and files on multiple computers because only a single master copy of the data must be maintained.
directory schema: The description of all object classes and objects within a directory, along with their attributes and inheritance structure. A Help file containing all the descriptions in the schema is included with the SDK.
directory service agent (DSA): A Microsoft Exchange Server component that handles the storage, maintenance, replication, and routing of addressing and other information.
directory synchronization: An automatic process of directory replication between Microsoft Exchange Server and a foreign system that is executed on a regular basis by the directory exchange agent (DXA) for a Microsoft Exchange Server organization. Directory synchronization allows the two systems to keep all copies of the directory identical. Synchronization between Microsoft Exchange Server sites and foreign mail systems can be performed using an application such as the DIRSYNC sample application.
discretionary access control list (DACL): A list used by the Microsoft Exchange Server directory to control access to its objects. A DACL consists of a list of security identifiers (which identify users) and specific permissions for each.
display name: The name of an object as it appears in the address book. For example, the Display-Name (an attribute in the Microsoft Exchange Server directory) of a recipient-class object is constructed of the strings Given-Name and Surname.
distinguished name (DN): The combination of an object’s name and its entire path. Each distinguished name is unique. A DN allows users and applications to access objects without knowing their physical location.
distribution list (DL): A MAPI address book object that represents a set of individual recipients addressed as a group and that implements the IDistList interface. Distribution lists can contain other distribution lists and individual recipients. A distribution list is one of two types of MAPI address book objects: either an object that can receive messages or a mail user object.
DLL (dynamic link library): A library of functions that uses dynamic linking. This allows an executable module to include only the information needed at run time to locate the executable code for a DLL function. Dynamic linking can be either load-time linking, causing the inclusion of the DLL code at load time, or run-time loading, causing its loading only when actually called by using the Windows LoadLibrary and GetProcAddress functions to get the starting address of a DLL function.