Abstract: Mechanisms for updating an address book. A first computing system generates an address book update file format and provides the file to a second computing system. The file format contains several data fields. One of the data fields consists of a configurable list of attribute property identifications. These property identifications represent address book information such as e-mail address, phone number, first name, surname, and the like. A second data field comprises contact data that includes at least some of the properties identified by the configurable list. Changes to the information contained in the address book update may be made by simply adding or deleting attribute property identifications. This has the effect of allowing modifications to the address book file format without having to generate a new file format.