Thanks for the reply. I wanted to clarify myself on my initial email. I wanted to block all SMTP from within the LAN out to the INTERNET from all devices accept the internal Mail server.
We caught a machine that was acting like it’s own email server and was possibly sending emails out from within the LAN out to the INTERNET without relaying it to our real mail server.
is that still not possible? or with that information, there are some hopes.