nanog mailing list archives

Re: Possibly OT, definately humor. rDNS is to policy set by federal law.


From: Tony Finch <dot () dotat at>
Date: Sat, 17 Mar 2007 14:09:42 +0000


On Sat, 17 Mar 2007, Rich Kulawiec wrote:
On Sat, Mar 17, 2007 at 01:09:47PM +0000, Peter Corlett wrote:
Would you care to expand on why you think sender callback
verification is apparently abusive and supports spam?

(a) this is wandering off-topic and (b) this has been covered in great
depth on Spam-L multiple times, so I'll refer you there for more
substantive discussion; consider this merely a brief overview whose
points are not particularly well-ordered, although I'm going to try
to list them from abstract-to-applied.

You failed to mention that callbacks encourage spammers to use real email
addresses instead of bogus inventions, thus making the backscatter
problem worse. Also, a non-working sender address is not well correlated
with spam: there are lots of legitimate but broken senders, such as mail
servers which reject MAIL FROM:<> and web servers which send MAIL
FROM:<wwwdata@webserver> and don't have an SMTP listener.

Tony.
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