Re: [Asrg] Re: Asrg Digest, DNSBL BCP v.2.0

On 3/3/07, gep2(_at_)terabites(_dot_)com <gep2(_at_)terabites(_dot_)com> wrote:

> I think you can do FAR BETTER from a content standpoint
> (content analysis, such as Spam Assassin, following "a
> priori" blocking of mail from unknown/untrusted senders
> containing HTML or attachments) than you can using any
> kind of IP-based blacklisting or other "reputation"
> scheme.
SpamAssassin (and other content filters) don't actually work the way
you think they do, on many levels.

The major measurable component of spam is whether or not the sender
has permission to contact the recipient. Content filters in particular
have no view into consent; no way to measure consent. There is no HTML
code or X-Header that reliably provides proof of opt-in. They do some
good things based on modeling of what looks like spam; but it's also
true that things that look like spam are not always spam. False
positive issues you rant about occur just as often with content
filters. Some would claim, even more so!

With a blacklisting, I get a bounce back and can find somebody to
argue with. With the common method of implementing a content filter,
my mail is quietly eaten and I get no information back regarding the
failure to deliver the mail to end recipient. This is worse than IP
blacklisting; less transparent; less obvious; less opportunity for
feedback and investigative recourse.

The fact that you think they're better is likely based on an
incomplete view on your part. You actually probably have no idea how
much of your mail has ever been redirected to a bulk or trash folder
by a content filter.

And of course, not to mention that SpamAssassin, which you hold up as
the better model, has lovingly crafted hooks into it to allow direct
support of IP-based blacklist and other IP-based reputation
mechanisms.

Note to rest of world: I'm not anti-SpamAssassin. I've run it myself
before and likely will again. I'm just pointing out that like just
about every other kind of spam filtering or blocking mechanism, a
content filter is imperfect. It's a bit mind-blowing to see content
filtering held up as this panacea to address the ills of IP-based
blocking, since they're both approximate models of what somebody
thinks is spam, and have flaws inherent to both technology and policy
limitations.

Regards,
Al Iverson
--
Al Iverson on Spam and Deliverabilty, see http://www.aliverson.com
Message copyright 2007 by Al Iverson. For posts to SPAM-L, permission
is granted only to this lists's owners to redistribute to their sub-
scribers and to archive this message on site(s) under their control.

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