local mail system should be only locally

[Sebastian Wolfgarten]

Hi,

I have got a working mail system here with some
local users which is used to send mail between
the users in an intranet. It works pretty fine,
but now I have got a question: I don't want the
local users to be able to send to any other host
than this one here (intranet.mynetwork.com).
How can I do this?

Bye
Sebastian