1. A method for processing a request to display an electronic message, the method comprising the computer-implemented steps of: generating first message data, wherein the first message data defines at least a first message portion and one or more selection regions for one or more other message portions of a multiple-part electronic message having a plurality of message portions; providing the first message data to a client; receiving from the client a request for a second portion of the electronic message selected from among the other message portions; generating second message data which, when processed at a user interface of the client, causes the client to display the second portion of the electronic message; and providing the second message data to the client.