Q. I am probing an Exchange server with the SMTP probe. The device stays green even when I enter a bogus email address.
A. This is a problem with your mail server accepting the bogus address. This is the relevant debug log entry:
Cmd line 12: MTCH m"^25[0-9]" else goto #31
14:38:55 CTCPProbeScript::NotifyReceivedLine(252 2.1.5 Cannot VRFY user, but will take message for <[email protected]>)
It returns a response in the 250 range, which is a positive response. You can see in the debug entry above that although the mail server cannot verify the user, it accepts the message anyway and sends the 250 range response that the probe expects. You will need to configure your mail server to reject addresses it cannot verify for the probe to work.
Alternatively, if you would rather that the 252 response be considered an error for your purposes, you could always modify the probe.