Abstract: An authorisation server (11) is provided which attempts to classify messages as being wanted or unwanted messages. If a message is classified as an unwanted message it is stored in a black inbox (18) as part of an archive of unwanted messages If a message is classified as a wanted message it is sent to a user's grey inbox (19) where the message can be reviewed. For messages whose status as a wanted or unwanted message is unclear the authorisation server (11) delays dispatch of such a message so that the message's status can be reassessed using additional information received about similar messages. This further information is received either from honey pot computers (12,13) set up to receive unsolicited messages and also from user rejection of similar messages previously dispatched to users' grey inboxes (19) during the period of delay.