In a client 20, an operation accepting section 22 obtains a primary address entered in an address entry field, and a transmitting section 21 sends the primary address to a mail server 10. In the mail server 10, a receiving section 19 receives the primary address; a message generating section 13 generates a message including out-of-office information corresponding to the primary address; and a transmitting section 11 sends the message to the client 20. In the client 20, a receiving section 29 receives the message, and a display section 24 displays an out-of-office message that a user corresponding to the primary address is away, and thereafter displays detailed information including buttons for setting an alternative address according to a click operation on a specific portion. An address updating section 26a displays an alternative address in the address entry field according to a button click operation.