Open Relay Checker before Opening MTA
bje at redhat.com
Sun Feb 10 11:10:35 EST 2002
>>>>> "Michael" == Michael Still <mikal at stillhq.com> writes:
Michael> Greg Lehey's mail server does something similar to this. It also looks up
Michael> the reported IP address in DNS and checks that it resolves the the
Michael> hostname that the machine claimed. I am not sure what MTA he is using to
Michael> do all of this though.
He uses Postfix:
Connected to mx1.lemis.com.
Escape character is '^]'.
220 wantadilla.lemis.com ESMTP Postfix
I tried using Postfix's anti-spam options to do the same thing. In
the end, I had to revert the change because I was rejecting far too
much legimate mail.
Trivia question: how many mail servers out there do you think have no
PTR records or if they do, don't match the name presented in their
HELO/EHLO? Answer: Lots.
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