Data transmission device, data transmission system and address registration method

The present invention relates to a data transmission device, a data transmission system and an address registerring method. The data transmission device receives an instruction from a user via a user interface to search for address information registered in an LDAP server. An address management module of the data transmission device acquires the address information from the LDAP server, and a list of the address information is displayed to the user. When instructed by the user to register a piece of the address information, the address management module acquires an absolute path from the LDAPserver, and requests an address management device to register the absolute path. The address management device registers the absolute path and notifies the address management module that the absolutepath has been registered.