[Exim] From the FAQ: Q9802

Hi there,

Reading the FAQ I came across “Q9802:  How do I configure Exim so that
it sends mail to the outside world only from a restricted list of our
local users?”

I thought that was really nice. But surely this would be kind of
pointless if people could just give out their email address via web
pages etc and still get email? How could you prevent the email coming
back to your server without killing the users email access altogether?

Thanks

Gary