From: Yakov Shafranovich <research(_at_)solidmatrix(_dot_)com>
[..]
It would be really swell if people proposing or criticising mechanisms
would pay attention to what they know (e.g. there's a lot of spam),
what they strongly suspect (*some* spammers do or do not remove in
response 550's), and what they wish (*most* spammers do or do not
respond to 550's).
Is there anyone out here that has some info on what spammers actually do
with "550" and other error codes?
Part of paying attention to what one knows, strongly suspects, and only
wishes ought to be distinguishing what can be known from that which can't.
Only spammers know what they actually do with SMTP error codes, and
they only know what they and their closest colleagues do. A description
of what "spammers actually do" in this context makes less sense than
the report of the committee of blind men describing the elephant,
because elephants don't change. Whatever spammers do today, if they
need to, they might switch tomorrow.
What does it mean to talk about "spammers"? There are only 500-1500
serious spammers today, but they use many different tools. They often
use their tools quite differently.
Say you found that 87.345% of all spammers today respond to 550's.
You could not conclude (or know) anything about yesterday or tomorrow.
Would you count "spammers" by counting spammer noses or spam email?
What if one of the "leads clubs" manages to recruit 100 new "home
workers"? (Yes, I'm mixing species of spammers). Whether you count
noses or spam, your percentage would surely be invalidated by whatever
the new spammers do.
Vernon Schryver vjs(_at_)rhyolite(_dot_)com
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