13. A computing system, comprising: one or more processors; memory; and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, the one or more programs including instructions for: displaying a messaging application for a first user; responsive to a determination that a message body of a first electronic message satisfies a first set of content-based clustering rules associated with a first message cluster, assigning the first electronic message to the first message cluster, which has a first plurality of electronic messages, wherein each electronic message in the first message cluster is either addressed to the first user or originates from the first user; displaying a first view of a first cluster graphic for the first message cluster, wherein the first view collectively represents the electronic messages in the first message cluster; in response to a first predefined user action, displaying a second view of the first cluster graphic, wherein the second view replaces the first view and displays the first plurality of electronic messages individually within the first message cluster; and in response to a second predefined user action, expanding one or more electronic messages of the first plurality of electronic messages inline within the first message cluster.
17. The computing system of claim 13 , wherein the first electronic message further satisfies a second set of content-based clustering rules associated with a second message cluster; and the one or more programs further include instructions for: assigning the first electronic message to the second message cluster; and formatting for display, in an electronic message folder of the messaging application, the electronic messages in the second message cluster as a second cluster graphic.