Exchange 5.5, had an open relay. Applied SP, some hotfixes, closed up the relay. But now internal Mac clients cant send email. How can I configure exchange to relay internally, but not from external ...

Hi. How does one determine if an Exchange 5.5 server is an open relay, and if so, disable that relay?<BR><BR>I was under the impression one of the exchange servers we have here wasn't a relay, however ...