Patent ID: 7558827

Claim:
A mail delivery system comprising: an alias mail processing unit that receives an alias mail addressed from an originator address to an alias address generated from a recipient address and a predetermined generation argument, restores the recipient address and the generation argument from the alias address, replaces the alias address in the alias mail with the restored recipient address, and replaces the originator address in the alias mail with a reply destination address generated from the restored generation argument and the originator address to transfer the alias mail to the recipient address; and a reply mail processing unit that receives a reply mail addressed from the recipient address to the reply destination address responding to the alias mail transferred by the alias mail processing unit, acquires the originator address and the generation argument from the reply destination address, regenerates the alias address from the acquired generation argument and the recipient address, replaces the reply destination address in the reply mail with the acquired originator address, and replaces the recipient address in the reply mail with the regenerated alias address regenerated to transfer the reply mail to the originator address.