With postfix installed, you can configure it to relay mail from post 25 up to James on post 8025 quickly with these steps.
(With a ubuntu postfix, the config is installed in /etc/postfix)
1) cd to /etc/postfix and edit main.cf. Add these lines to the bottom of the file.
- This enables the Transport Map and allows any names to pass on through.
#Enable transport maps transport_maps = hash:/etc/postfix/transport local_recipient_maps =
2) Create a file /etc/postfix/transport with these contents. If you have a real hostname responding to your MX, replace localhost with that real hostname.
#When modifying this file use the command "postmap transport" to update the db localhost smtp:localhost:8025
3) Run the commands "postmap transport" and "service postfix reload" and you're all set. Watch the /var/log/mail.log for any mail forwarding messages.