I don't think so. This is NOT standard practice.
Now, if you said no CNAME and A records, otherwise a PURE NXDOMAIN, then
yes, there is a growth in these types of ANTI-SPAM techniques.
We do it ourselves in our WCSAP package with includes CBV. If there is
no MX/CNAME/A, the transaction is rejected with a 45x.
This works nicely with a similar GREYLISTING effect because the BAD GUYS
do not try again. The GOOD GUYS do have legitimate setup.
Finally, in the past week we been helping a new customer and he didn't
have his MX record setup and he still doesn't as of today.
The fact that we been communicating back and forth via our support email
channel means that the A record fallback is STILL an EXPECTED standard
in SMTP. If we used this MX only idea, we would never be able to
communication with him.
Anyway, I'm not saying you can't use this technique as part of a total
ANTI-SPAM concept, but that it shouldn't be part of the SSP concept.
--
Sincerely
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com
Bill(_dot_)Oxley(_at_)cox(_dot_)com wrote:
A friend with a small local mail server that ONLY sent out good,
legitimate mail was blocked by almost everyone for lack of an MX record.
Old days are gone.
thanks
Bill Oxley
Messaging Engineer
Cox Communications
404-847-6397
-----Original Message-----
From: Hector Santos [mailto:hsantos(_at_)santronics(_dot_)com]
Sent: Wednesday, June 06, 2007 8:16 AM
To: Douglas Otis
Cc: Oxley, Bill (CCI-Atlanta); IETF DKIM WG
Subject: Re: [ietf-dkim] RE: I think we can punt the hard stuff as out
ofscope.
Douglas Otis wrote:
A single policy record placed adjacent to the domain's MX record could
be sufficient. This would eliminate domain transversals or wildcard
search mechanisms. However, this approach creates a need to obsolete
the use of just A records as an SMTP server discovery/confirmation
method. Once an A record discovery/confirmation has been obsoleted,
then messages might not be accepted when the email-address domain is
not
confirmed by the existence of an MX record.
Doug,
The MX/CNAME/A discovery process is long established process and part of
the SMTP standard for millions of systems world wide, not just the
Fortune 10, 500, 1000 or 10,000, and it includes legitimate systems with
no MX records but with a CNAME or A record.
And you want to change this long established methodology for SSP
purposes?
You're kidding right?
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