The present invention restrains growth in data size of electronic mail to be managed, and thereby helps manage electronic mail efficiently. This mail server device comprises: a mail reception means that receives electronic mail; a mail header reading means that, when electronic mail is received by the mail reception means, separates the received mail into shared mail information including body text and a header part; a first storage region; and a second storage region which is differently allocated for each destination of electronic mail, wherein the mail header reading means stores the shared mail information of the received mail in the first storage region, and stores the header part of the received mail in the second storage region allocated for each destination of received mail.
