PURPOSE: To prevent the occurrence of the missing of specifying a reply destination in the case of communication by a mail recipient whose reply communication is required by setting sender information to the reply destination information and sending a mail when a reply mail is required for the recipient.

CONSTITUTION: A transmission mail destination designating means 4 is used to designate a recipient of a transmission mail generated by the user with a transmission mail generating means 3. When a mail sender requires a reply from the recipient, the sender designates the necessity of a reply request and generates a transmission mail parameter table when plural recipients are present thereon. A transmission mail reply destination setting means 5 references the table and sets a reply request to the reply destination information to generate other transmission mail parameter table. When the means 4 designates the necessity of the reply request in such a manner, then the means 5 automatically sets the mail sender as the reply destination. Then the mail transmission means 6 stores the transmission mail parameter table having the information at every destination to a mail box file 7 to be sent.