1. A method for searching for address book information by an apparatus for searching for address book information, the method comprising: upon receiving search request messages for searching for address book information in at least one external directories from a plurality of requesting clients, checking search preferences corresponding to the plurality of requesting clients in a database; creating external search request messages corresponding to the at least one external directories associated with the search request messages based on the checked search preferences; forwarding the external search request messages to the at least one external directories; upon receiving external search results from the at least one external directories, applying the search preferences to the received external search results to create final search results; forwarding the created final search results to the plurality of requesting clients; and updating the search preferences based on the final search results.