To perform a mail address cleaning operation with a repeater instead of a mail server.

The repeater is connected to a cellphone having a function for performing applications for the cellphone and to a mail server having a function for transmitting/receiving mails. The repeater has the function to store a user identification number of the cellphone to which a mail cannot be sent from the mail server, the function to hold a communication module which operates within the cellphone in order to communicate with the repeater, and the function to determine whether or not a mail address is correct for a connection request from the cellphone performed in starting the applications for the cellphone and to return the result to the cellphone. The cellphone has the function to receive the determination result and to prompt inputting of a correct mail address when the mail address of the cellphone is not correct.