Exchange 2007: Stopping email spoofing for internal users
We get a ton of spam email claiming to be sent from users inside our organization to users in our organization. Upon examining the message properties, it is clear that they are being sent through an outside SMTP server. How can I make it so Exchange treats any email sent through an outside SMTP server from an internal address as spam? None of my users need to be able to use an outside SMTP server anyway so it won't interfere with them. Thanks.