On Mon, 29 Jan 2007, Dick St.Peters wrote:
John Q Spammer owns johnsspamdomain.com, so the name-->IP resolution
is under his control. He connects to my mail server with IP a.b.c.d
and gives HELO name "mail.johnsspamdomain.com". I check what that
resolves to and find it resolves to a.b.c.d. Then I check what
a.b.c.d reverse resolves to and get port6.box4.dialup.isp.pl. Guess
what I use the PTR for.
That is fine, but PTR did *not* help you authenticate connection.
It was a genuine authentic johnsspamdomain.com HELO name - and you
knew that without checking PTR. Any reputation points can
properly be assigned to johnsspamdomain.com:HELO. It was not forged.
I am not complaining about using PTR as part of a spam detection
heuristic. I do it myself. I am complaining about using PTR to
*authenticate* the connection.
spam != forgery
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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