A method of sending an e-mail from a mail source to one or more destinations at their respective mail addresses through a source mail server, which manages a mail address of the mail source, and a destination mail server, which manages another mail address as a destination mail address of the destinations, comprising:
- registering, by a mail address manager interconnected between said source mail server and said destination mail server, when the destination mail address of the particular destination has been updated, the old destination mail address of the particular destination and a new destination mail address in correlation with each other;
- temporarily storing a particular e-mail, by a mail storing section interconnected between said source mail server and said destination mail server, which is addressed to said old destination mail address, until said new destination mail address is registered by said mail address manager;
- and
- sending an e-mail, by a mail sending section interconnected between said source mail server and said destination mail server, which is addressed to said old destination mail address, to said new destination mail address if the last-named e-mail is addressed to said old destination mail address.