2.2.3 Properties that Apply to All Address Book Objects

Address Book objects are listed in an offline address book (OAB) by the OAB Format and Schema Protocol, as specified in [MS-OXOAB], or accessed on an address book server by using various NSPI method calls,<9> as specified in [MS-NSPI] and [MS-OXNSPI], or by using various HTTP request types for an address book server endpoint,<10> as specified in [MS-OXCMAPIHTTP]. Each object represents any addressable entity, including but not limited to mail user, distribution list, Department object, Organization object, address book container, or Resource object. Not all properties defined in this section are stored in the OAB. For a list of the properties stored in the OAB, see [MS-OXOAB].

It is possible to set any Address Book object as an addressee of an outbound message to be sent by a messaging client. A mail user is an example, and it can contain an e-mail address to be used for messaging. A distribution list is a special type of Address Book object that represents a collection of other Address Book objects, can be an addressee of an outbound message, and SHOULD have additional properties, as specified in section 2.2.6. Mail user objects are further broken down into subtypes, such as rooms, equipment, messaging forums, or other types. Note that servers can restrict client access to specific properties as required by the implementation. One example is distribution list membership; the server can restrict access to distribution lists in which the members are hidden.

The Department object and the Organization object are types of Address Book objects that are required to support a hierarchical address book view that messaging clients need.