Abstract: A message consignor transmits messages, recipient information regarding the intended recipients of the messages and day/hours information designating the day and hours for communicating each message to a message management site via a telephone network if an attribute of the message is voice or via the Internet if an attribute of the message is an e-mail. The message management site stores these messages, recipient information and day/hours information in association with one another, and transmits a message regarding which the day and hours designated by day/hours information associated with it have arrived via the telephone network if an attribute of the message is voice or via the Internet if an attribute of the message is an e-mail, on the basis of recipient information associated with the message. In addition, automatic conversion of a message attribute and association of a plurality of messages with one another are also accomplished.