A method of selecting a recipient of a message on the basis of data identifying access to previously transmitted messages, wherein each said message includes content data for display within a display area of a receiving terminal and control data including data indicative of a user selectable portion within the display area. The method includes receiving content data having one of a plurality of different types for use in creating said message, accessing tracking data corresponding to a previously transmitted message containing content data of a given type, the tracking data being indicative of selection of said user selectable portion upon display thereof at said receiving terminal, and selecting a recipient of the message on the basis of the received content data and the tracking data.