A service e-mail providing system includes n (n is an integer more than m, and m is an integer more than 1) terminals which are connected a communication network. An e-mail server is connected with the communication network, and has an e-mail database in which a service e-mail and an advertisement e-mail are stored, and the advertisement e-mail contains advertisement data. The e-mail server transmits the advertisement e-mail to a first one of m terminal of the n terminals, such that the advertisement e-mail are transferred between the m terminals, users of the m terminals satisfying the transfer constraint condition. When a transmission condition is satisfied during the transfer of the advertisement e-mail, the e-mail server transmits the service e-mail to the m terminals.