My quick 2-cents (pre-caffination)
I did find the best approach to this obscure anti-spam defence ,was to
have an bogus MX at the highest and lowest MX priority
I got some stats a few months back from a spam tarpit I built and
discovered that spammers tend to go for either the highest or lowest MX
prioirity and nothing else. (I only had a small sample set though) . Or
maybe I should say that I "felt" my anti-spam defence was optimal when I
adopted this approach.
If an MTA is non-RFC compliant then it really shouldn't be taken into
account. The rules are ther for a reason, despite the business reality.
On Fri, 2007-11-09 at 11:20 +0000, Rob Gallagher wrote:
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>> On 09/11/2007, Jimmy Tang wrote:
> > have people tried no-listing? setting up the primary mx record such that
> > it *does not receive mail* at all, and working on the assumption that
> > a real mailer will fall back to the secondary(s) to try and send the mail, where
> > in the case of a spammer they are less likely to try again on the secondary which
> > will do your usual filtering if you need/want it to.
>> Spammers will often bypass the primary MX entirely in the hope that
> the secondary has more lax filtering policies, which is often the
> case. Also, there are many MTAs out there that do not behave like
> "real mailers" or as we would like them to behave (ie: RFC-compliant),
> and may react badly to something like no-listing.
>> On the face of it, no-listing *seems* like a good idea but if you sit
> down and think about it its really just security through obscurity and
> creates more potential problems than it solves.
>> - --
> rob.gallagher (at) gmail.com || www.spoofedpacket.net || PK: 0x1DD13A78
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