I have a LAN with Windows9X/XP machines running Outlook 2000. The server is a RedHat 7.3 permantly connected to Internet by an ADSL router. Since now every computer receives/send its internet mail directly from our ISP while the internal mail (from or to the other computers of the LAN) is based on the Microsoft Post-Office (the one than comes whit Windows 95).
I want the Linux server to become the email server of the LAN. In order to do that I have installed Postfix, Fetchmail & ipop3d. I want the server to behaivour as follows:
I (Joseph) want to send an email to the internal user Susan. Postfix must deliver the message localy and Susan must see on the From: joseph@mmm.local.
If I want to send an email to the external adress john@rrr.com Postfix must send the message to Internet and john must see on the From: joseph@ggg.net.

Can anybody give me some advice?

(sorry for my english)