I have an exchange server 2000 sending messages to internet with a Send Mail, my problems is the Send Mail not validate the user list when the messages are outgoing to internet, everybody can send messages outside my organization, what cand I do to limit this ? Alan Leyva Cimex, S.A. Ing. Alan Leyva Acosta Esp. Sistemas Computación Datacimex, Corporación Cimex, S.A. alanleyva@xxxxxxxxxxxx 203 9453