A net database holds, for each user, user information which contains information indicating a forwarding destination (FAX, Web, portable terminal, or the like) of a received e-mail message, and information indicating a destination to which a message indicating that an e-mail message is forwarded is to be sent. A site which includes a judgment module and conversion module converts a received e-mail message into a data format matching the forwarding destination designated by the user information using the self function or in collaboration with another site. The converted data is forwarded to a mail server, Web server, or FAX server in accordance with the designated forwarding destination. When the e-mail message is forwarded via the Web server or FAX server, a message indicating this is sent to a portable terminal via the mail server.