From: "Hector Santos" <hsantos(_at_)santronics(_dot_)com>
Now, consider the result codes. Lets suppose you are not an open relay,
are indeed a delay validation system. In this case, you will get a
result code hence the CBV passes the test.
RCPT TO: <random address/domain>
55x User not found
That should be:
55x Not Authorized to Relay mail
55x NULL can not relay mail
To match the idea that you are not an open relay. "55x User not found"
would had implied you were doing a dynamic RCPT validation.
Hector Santos, Santronics Software, Inc.