Organizing messages received and transmitted over a network is described. In one aspect, a method includes tracking where a user is gazing as the user is composing an outgoing message on a first computer system. During a composition time period in which the user is composing the message, a relevance rating for one or more of a plurality of gaze areas is determined. The relevance rating of a gaze area is based on a number of times the user's gaze dwells on the displayed message associated with the gaze area after the user's gaze is directed away from the displayed message. The method further includes identifying at least one displayed message that is related to the outgoing message based on at least one of the relevance ratings, and associating an identifier for at least one of the at least one related message with the outgoing message.