Re: Bouncing Spam

On Mon, 19 Mar 2007, Ellad Tadmor wrote:

> Thanks for the reply. So I guess what you are saying is that the bounced
> message does not reach the spammer, but an innocent site used by it. I can
> see how that would be annoying.
>
> However, it seems to me that it is your responsibility as the
> administrator/postmaster to prevent spam from being distributed off your
> domains. Just like individual users should install anti-virus software to

No, what he is saying is that spammers forge email headers to appear as if
they come from his domain and users. His physical servers aren't part of
the mail flow. If you know how to read mail headers, it isn't hard to
detect this case, but software has a hard time because of the many
variations.

I disagree with his belief that spammers actually remove complainers in a
world where the marginal cost of each mail sent is in the small fraction
of a cent, there is no motivation to remove and address and in fact
receiving complaint validates the address. About 85% of all mail is spam
sent to non-existant users. What is the motivation to raise that
percentage by deleting real users?

One of the very hard issues in tracking spam is the hugh variability in
what is sent and how much. As an individual there is no statistically
valid conclusion to draw from apparent spam receipt changes. My daily dose
of spam has varied between < 200 to around 400. I unsubscribe from
legitimate commercial sources and that usually works, but otherwise
just let my filter chuck it.

Dave Morris
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