Patent ID: 7752282

Claim:
An address information managing system comprising: a processing apparatus comprising: an update request issuing unit issuing an update request, containing address information to be updated, in order to update an address book of said processing apparatus retaining the address information about other processing apparatuses; and an updating unit updating said address book on the basis of a response result to the update request issued from said update request issuing unit; a valid address list showing valid address information; a determining unit, when receiving the update request issued from said update request issuing unit of said processing apparatus, searching for the address information contained in the update request in said valid address list, determining that the address information is valid when the address information is found in said valid address list, while determining that the address information is invalid when the address information is not found in said valid address list; a response result transmitting unit transmitting a result of determination made by said determining unit to said processing apparatus as the response result to the update request, wherein said address information managing system further comprises: a change history table showing a relationship between current address information retained in said valid address list and former address information that had been used until the address information was changed to the current address information; and a current address information obtaining unit searching for the address information contained in the update request in said change history table when said determining unit determines on the basis of the valid address list that the address information is invalid, and obtaining current address information retained in said valid address list corresponding to the address information contained in the update request from said change history table when the address information is found in the search, wherein said response result transmitting unit transmits the current address information to said processing apparatus as the response result when said current address information obtaining unit obtains the current address information, wherein, when said updating unit of said processing apparatus receives the current address information, as the response result, obtained by said current address obtaining unit from said response result transmitting unit, said updating unit overwrites the address information to be updated with the current address information in said address book.