rsk at gsp.org
Sat Feb 20 07:08:23 CST 2010
On Fri, Feb 19, 2010 at 08:20:36PM -0500, William Herrin wrote:
> Whine all you want about backscatter but until you propose a
> comprehensive solution that's still reasonably compatible with RFC
> 2821's section 3.7 you're just talking trash.
We're well past that. Every minimally-competent postmaster on this
planet knows that clause became operationally obsolete years ago , and
has configured their mail systems to always reject, never bounce. 
For the rest, that are still sending backscatter/outscatter spam on
a chronic/systemic basis, we have spammer blacklists, since
of course they *are* spamming.
It should be obvious on inspection to everyone that one of the very
last things we should be doing when we are drowning in useless/junk
SMTP traffic is to generate more of it.
Doubly so when, as we have seen, abusers have demonstrated the ability
to repurpose it as a formidable weapon.
 Thanks in part to the rise of the zombies, to the ready availability
of cheap/free domains in bulk, to anonyous/obfuscated registration, to
fast-flux DNS, and to a number of other factors. And no, SPF does not
in any way mitigate this problem. Neither does DKIM. Neither does
SenderID. Neither does *anything* except not sending it.
 Yes, there are occasionally some edge cases of limited scope and
duration that can be tough to handle. However, well-known methods exist
for minimizing these in various mail environments (e.g., front-end/back-end,
multiple MX, etc.), and these have been elucidated and discussed at length
on the relevant mailing lists, such as spam-l. The key points here
are "limited scope" and "limited duration". There is never any reason
or need in any mail environment to permit these problems to grow beyond
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