its tow days i've been reading tutorials on the internet but still havent got a clear explanation for this:
how can I configure postfix so that local users can send/receive emails with eachother without the need of the internet connection and if they want to communicate outside our Lan they can use the internet connection.

the server admin is on vacation and I know little about postfix but from what I see, right now the mailserver is configured so that an internet connection is needed so that users can send/receive emails, but since we are having problems with the ISP we want the users to at least be able to communicate with each other.