27. The method as recited in claim 1 , wherein the plurality of content portions linked to the single message item include: an electronic message relationship field representing a link to an electronic message, the link indicating that the portion of message content is associated with an electronic message; a content type field representing a content type corresponding to the portion of message content; an order field representing an order value, the order value indicating how the portion of message content is to be ordered with respect to other portions of message content that are also associated with the electronic message; and a content properties field representing additional properties of the content type represented in the content type field.
29. The method as recited in claim 27 , wherein the content properties field comprises: a MIME URL field representing a link to a MIME path that corresponds to the portion of message content.