1. In a computer system that is network connectable along with one or more other computer systems to a network, a method for creating an electronic message that can be stored and accessed with increased efficiency, the method comprising: an act of creating a message item representing the electronic message in accordance with a message schema, the message item having one or more general properties that may be common to a plurality of different types of message protocols and message applications; an act of assigning a primary type to the created message item, the primary type indicating a primary behavior of one or more content portions linked to the created message item; an act of assigning one or more protocol extensions to the created message item, each assigned protocol extension adding one or more protocol specific properties to the created message item so as to promote compatibility between the one or more linked content portions and a specified message protocol; and an act of assigning one or more application extensions to the created message item, each assigned application extension adding one or more application specific properties to the created message item so as to promote compatibility between the one or more linked content portions and a specified message application.