Method of transmitting a message with duration of validity destined for a subscriber terminal, comprising the formulating, in the message, of a field containing information regarding duration of validity of the message and the monitoring of the validity of the message on the basis of the information contained in said field, wherein the message is transmitted to the terminal of the subscriber and, on the expiry of the duration of validity of the message, the message received by the terminal is modified or deleted in such a way as to prevent consultation thereof.