-----Original Message-----
From: M Wild [mailto:asrg(_at_)wildm(_dot_)com]
Sent: Tuesday, March 18, 2003 2:04 PM
To: asrg(_at_)ietf(_dot_)org
Subject: [Asrg] Amend the RFC to require reverse DNS
Greetings - One of the most effective anti-spam measures I have taken on my
mail servers is to require the sending mail server's IP address to reverse
resolve to the name it uses in its HELO command. While this is a violation
of the RFC it eliminates lying machines and forces accountability on the
sending server. Yes, I know it can be forged or spoofed however it still
significantly raises the level of effort required on the part of the
spammer. I've had to turn this check off due to customer complaints
however
I am reconsidering this decision. Amending the RFC to *REQUIRE* correct
and
complete DNS setup for a SMTP client would go a long way towards reducing
my
undesired traffic. It would also address the customer (and clueless
administrator) complaints with a simple "I am following the rules" How can
you argue with that?
I can't- I like the idea.. but it has to go further than that.
Example: MOMandPOP.com hosts their website and mail systems at their local
ISP.
They send email as recipes(_at_)MOMandPOP(_dot_)com(_dot_)
Because their ISP has closed port 25, all email from MOMandPOP.com must go
to the relay server first.
You see at your end-
HELO megamail1.isp.com << reverse lookup of megamail1.isp.com shows an IP
address of 198.10.10.2
mail from: recipes(_at_)MOMandPOP(_dot_)com << reverse lookup of MOMandPOP.com
shows an
IP address of 198.10.210.53
In your example, this email would fail.
Even though MOMandPOP.com are real and just wanted to send you your
requested apple pie recipe.
The DNS needs a key or something that would define MOMandPOP.com as part of
mega.isp.com.
Please see the "Position paper, in zipped HTML" posts by Valdis Kletnieks.
Regards,
Damon Sauer
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