Please elaborate on what you need, I can help with this but need to know more what you are looking for.
this what i have
juniper ssg 140 , and server windows 2003 it contain exchange 2003
when i send from in ternal to any external e-mail it reach . but when i send from any outsid email like firstname.lastname@example.org it will not reach
i have my domain www.mydoamin.net
i create inside my domain MX record that mail.mydomain.net
i create opinter to send to my router by the external IP that i get from ISP , which is configure as external or Untrsut port.
now how to deploy my exchange to receive from outsid and let juniper to redirect any requiest to my exchange . and how to configure so i can use OWA from outside