Mail server

A mail server administering at least one domain and provided with a mail box for storing mails to a mail address having the domain, the mail server comprising:

• a memory section to store:
• (a) an address information table in which address information is registered that includes ability or inability to use each mail address having the domain;
• and
• (b) a notify party information table in which notify party information is registered that specifies each notify party to notify that a mail address having the domain cannot be used;
• an acquisition means to acquire mail addresses of a source and a destination of the received mail;
• and
• a control section for performing:
• (A) a first process to judge, referring to the address information table, whether the mail address of the destination is available or not;
• (B) a second process to judge, referring to the notify party information table, whether the mail address of the source falls within the notify party information;
• (C) a third process to create a reply mail stating that the mail address of the destination cannot be used;
• and
• (D) a fourth process to transmit the reply mail to the mail address of the source, wherein
• the control section creates the reply mail in the third process in a case where it is judged in the first process that the mail address of the destination is unavailable and where it is judged in the second process that the mail address of the source falls within the notify party information.