Various embodiments prevent erroneous transmission of electronic mails and therefore forestall information leakage in an electronic mail delivery apparatus. When an electronic mail is to be transmitted, a hidden letter selection unit presents a mail address specified as a transmission destination or source of the electronic mail with a part of the mail address presented as a hidden letter part. If a correct letter is entered in the hidden letter part of the mail address, a selective mail delivery unit executes the transmission of the electronic mail. If a correct letter is not entered in the hidden letter part of the mail address, the transmission of the electronic mail is stopped. Thereby, the effectiveness of operation for mail address checking can be improved, and the checking operation can be prevented from losing substance.