1.5 Applicability Statement

The original application of the algorithm was to permit the creation and representation of message classes other than simple email messages, and some additional attributes that were not natively supported by the transport protocol.

This application was further extended to allow the transport of the rich set of properties required by more modern messaging clients, including named properties. For backward compatibility with the original implementation, a special attribute is used to encapsulate the new message properties, and those properties with analogues to the original implementation are usually represented using the original attribute syntax.