Messaging Content Classes
Topic Last Modified: 2006-06-11
The Exchange store provides a set of content classes to identify items that are messages. The following table lists the content classes along with a brief description of each.
| Content class | Description |
|---|---|
urn:content-classes:message |
The base content class for all messages. This content class defines an item that is a message and a set of properties that describes the item. |
urn:content-classes:calendarmessage |
Extends the urn:content-classes:message content class and identifies a message that contains meeting requests, appointments, and so on. |
urn:content-classes:reportmessage |
Extends the urn:content-classes:message content class and identifies a message that is a report. Such messages include Delivery Status Notifications (DSNs) and Mail Disposition Notifications (MDNs). |
urn:content-classes:dsn |
Extends the urn:content-classes:reportmessage content class and identifies a message that is a DSN. |
urn:content-classes:mdn |
Extends the urn:content-classes:reportmessage content class and identifies a message that is an MDN. |
urn:content-classes:recallmessage |
Extends the urn:content-classes:message and identifies a message that is used to recall a previously sent message. |
urn:content-classes:recallreport |
Extends the urn:content-classes:recallmessage content class and identifies a message that contains a report about a recalled message. |
The following illustration shows the hierarchy of these classes:
|----> recallmessage -----> recallreport
|
message----> calendarmessage
| |-------> mdn
|----> reportmessage
|-------> dsn
Note
The recallmessage, recallreport, reportmessage, MDN, and DSN content classes identify a refined intent or purpose for items beyond simply being a message; no additional properties are defined for these classes. These content classes are good examples of the practice of using content class to refine the intended purpose of an item in the Exchange store. Content class definitions do not need to specify additional properties if those defined by the base class are sufficient. In your applications, you can use similarly defined hierarchies of content classes for the same purpose, such as making the intent or purpose of various items more specific. The calendarmessage content class, on the other hand, defines the additional urn:schemas:calendar:method property, which is specific to these types of message items.