smtp auth

Hello. I'm using PMG as a mail proxy for my Exchange mailserver. Yesterday I noticed that it's possible to send mails anonymously from the domains listed in my relay domains, to any other domain listed in my relay domains. I tested from an unrelated external network, and i was able to send...

We've been using PMG for a couple of weeks but today I saw our IP address seems to be on a Microsoft blocklist - ignore this part, how to get unblocked is not the reason why I am posting. Rather, I'd like to see how to get PMG to work with selective smarthosts or possibly some other suggestions...