[100364] in North American Network Operators' Group
Re: Misguided SPAM Filtering techniques
daemon@ATHENA.MIT.EDU (Sean Figgins)
Mon Oct 22 12:02:24 2007
Date: Mon, 22 Oct 2007 09:41:29 -0600
From: Sean Figgins <sean@labrats.us>
To: nanog list <nanog@nanog.org>
In-Reply-To: <C340CE72.101023%dave.nanog@alfordmedia.com>
Errors-To: owner-nanog@merit.edu
Dave Pooser wrote:
> Whenever I get one of those, I go ahead and confirm the message so the spam
> gets through to the end user. I figure if they think I'm gonna filter their
> mail for free, well, they get what they pay for. :^)
And that is probably just fine, as 99% of the true spam comes from email
addresses (and often doamins) that either do not exist, or often are not
configured to receive email. The result is that 99% of the spam filtered by
spamarrest (or other challenge-response techniques) is never actually seen by
any human. If you didn't send the the email, why bother confirming it? Aren't
you also adding back to the problem?
Even if you confirm your email address, that's all that spamarrest is asking
for. If the email address is valid, then it's done it's job. If the email
address is not valid, then the spam gets stopped.
I use a challenge-response system in conjunction with other techniques, and have
reduced the amount of spam I have to deal with by a couple orders of magnitude.
I also advise the list membership here that if they DON'T want to get the
challenge from my agent, they should send responses through the list.
As fas as the original poster... When I was working for a particular MSO the
topic came up for filtering port 25. It took me about a minute to convince them
that it was a bad idea, as a lot of people with broadband are the work-fro-home
type, and not all of them VPN into their work, but instead use their corporate
SMTP/POP/IMAP server to do their business. Since handling these valid servers
on a ticket basis would prove to be too much work, the plan was scrapped.
-Sean
(Please respond only to the list.)
