Abstract: When the distribution of distribution data is reserved, the band in use, distribution starting time and the like of the distribution data or already reserved distribution data are automatically modified depending on the type of the distribution method of additional distribution data, and a distribution schedule is adjusted.

Abstract: A multicast delivery system that prevents data from being lost. A group generating section in a multicast delivery unit divides data to be delivered stored in a database to generate a plurality of groups. A delivery times determining section determines the number of times each group is delivered. A delivering section repeats delivery of each group times determined by the delivery times determining section. In a multicast receiving unit, a receiving preparing section prepares receiving according to control information delivered by a control information delivering section before delivery of data, so a data packet receiving section can receive delivered data smoothly. When the receiving of the entire data is completed, a received data quality judging section judges whether the receiving was performed normally and informs a judgment responding section of a judgment.

Abstract: An electronic mail system that is used to send electronic mail with an attached file reliably regardless of the status of mail servers on a transmission path. In this electronic mail system, if an attached file is added to electronic mail sent from a mail client, being a sender, an attached file separating section separates the attached file from the electronic mail. An attached file transferring section transfers the attached file separated from the electronic mail by the attached file separating section to an FTP server. A store location information adding section adds store location information indicating a location where the attached file transferred by the attached file transferring section is stored to the electronic mail. The electronic mail to which the store location information has been added is sent to a receiver mail server.