Gets or sets the content type.

For inheriting types that have a string ContentType property, this property should be overriden to forward the ContentType property into the inheriting type's string property, and vice versa. For types that have a ContentType ContentType property, it is not necessary to override this member.

Gets or sets the data.

Gets whether the message is read only or not. This can be overriden by inheriting classes to specify whether or not the message can be modified.