we have an exchange 2003 server that routes mail to an isp using an internet connector. This connector uses a smart host at the isp. I ran the Exchange best practices analyser tool and 1 of the results was that the server is configured as an open relay. Since we route mail through an isp i suppose this isnt a prob.
But if i want to secure this server against open relaying how do i do this?
Yesterday i changed the props of the smtp virtual server > Access > Relay > and selected "only the list below" and also selected "allow all computers which successfully authenticate to relay, regardless of the list above".
All users afterwards could send external mail ok but some could not receive.
Have i missed something?