Patent ID: 7706825

Claim:
A mail exchange system, comprising: a plurality of terminal devices connected to one another via a communications network, each terminal device having a member information storage that stores member information of members who belong to a group that exchange mail via said communications network, said plurality of terminal devices comprising a specific member terminal, an existing member terminal, and a newly joining member terminal; said specific member terminal including: a participation mail receiver that receives participation mail, including member information of a member who newly joins the group, from said newly joining member terminal via said communications network; a first member information adder that extracts the member information included in the participation mail received by said participation mail receiver and stores the extracted member information in said member information storage; and a new member information mail transmitter that transmits a new member mail, including the member information of the newly joining member, to said existing member terminal according to information stored in said member information storage via said communications network, said existing member terminal including: a new member information mail receiver that receives the new member mail; a second member information adder that extracts the member information included in the received new member mail and stores the extracted member information in a member list in said member information storage; and a self-information mail transmitter that transmits an existing member mail, including self-member information, to said newly joining member terminal via said communications network, and said newly joining member terminal including: a new participation mail transmitter that transmits the new member mail, including self-member information of the newly joining member, to said specific member terminal via said communications network; an existing member information mail receiver that receives existing member mail from a plurality of said existing member terminals; and a member information generator that generates entries in said member list stored in said member information storage by extracting the self-member information from the received existing member mail from said plurality of existing member terminals, other than said specific member terminal, wherein a group ID, indicating the group exchanging the mail, is added to the mail to be exchanged among said terminal devices of the members belonging to the group, the group ID including user identification information of said terminal device of a member who forms the group and including a time when the group is formed, and wherein the group ID is a unique identifier for each group, is generated at said terminal device of the member who forms the group, and is generated exclusively by said terminal device.