Re: Fighting email spam and anti-UBE pointers
C-R Systems
>
>
> Archive-name: mail/anti-ube-pointer
> Posting-Frequency: 2 times a month
> Maintainer: Jari Aalto A T cante net
>
> Announcement: "Bounces, Challenge-response systems, MTA, Bayesian tools (article pointer)"
>
> Availability
>
> FAQ archive is at http://www.faqs.org/faqs/
>
> This message is an excerpt from bigger from Procmail Module
> Library project's README.html document titled "Procmail
> strategies against spam." available at
> http://pm-lib.sourceforge.net/
>
> The key points discussed in the document:
>
> - Auto-replying or bouncing is considered a bad tactic
That's absurd. Almost every corporation and organization in
the world does both.
You don't think that letting people know that their mail was
received (rather than being eaten by one of the dated spam
filters you recommend) or couldn't be delivered is a good idea?
> - Challenge-Response system is based on false assumption
> that sender's address can be used for authentication.
That's ridiculous. Challenge-Response systems are based upon the
assumption that spammers and trolls are using false return
addresses.
Which is true, 99.999% of the time.
Whoever produced this document is either extremely ignorant or
deliberately misleading the public.
Considering how many times they have been informed of its
erroneous content, the latter is the only reasonable conclusion.
Spammers and trolls HATE Challenge-Response systems, because theycannot beat them.
They can, however, beat the filters recommended in this post, and
do so all the time, because they are the world's foremost experts
in their use.
That's their _job/hobby_ They don't have anything else to do
with their time but figure out how to get their garbage in your
mailboxes.
And they can post whatever they want on the Usenet and the Web,
like anyone else.
Like this bi-weekly DISINFORMATIONAL article.
I wrote a simple Challenge-Response program that uses Procmail as
it's back end, and spam is no longer a part of my life. Period.
I don't even know when the spammers and trolls _try_ to get into
my mailboxes: Anonymous mail is rejected.
But no one I want to hear from has any problem reaching me.
Earthlink, as well as many other ISPs, offer Challenge-Response
systems as one of their basic spam-fighting tools.
Please Google the subject to get a real handle on it.
<snip>
> - MTA rejects can be abused and system administrators should
> check their setup at least in regard to viruses.
> - Challenge-Response system is based on false assumption that sender's
> address can be used for authentication. It cannot and thus any C-R
> system will contribute nothing else by amplifying the spam problem.
>
> See picture http://pm-lib.sourceforge.net/pic/cr-system-joe-job.png
>
> What should be done then?
>
> - Bayesian tools are non-intrusive, harm no third parties
> (in contrast to C-R), are easy to use and provide a good shelter.
> - Battery of bayesian tools give even better shield due to
> each program using a slightly different algorithm.
>
> Many clarifying pictures are included:
>
> - How address harvesting works
> - How viruses should not be treated (at MTA level)
> - Challenge-Response based authentication (overview)
> - Challenge-Response system causing "Joe-Job"
> - How MTA level UBE prevention works
> - Procmail with battery of statistical tools
>
> Table of contents:
>
> 1.0 Thoughts about increasing spam annoyance
> 1.1 Bouncing messages do no good
> 1.2 Rule based systems are not the solution
> 1.3 Challenge-Response systems make matters worse
> 1.3.1 Challenge-Response is not a doorbell but a
> gun shooting decoys
> 1.3.2 Questioning Challenge-Response systems implementations
> 1.3.3 Summary - What are the effects of Challenge-Response
> systems
> 1.4 Spam appearing in your yard - a story
>
> 2.0 A lightweight UBE block system with pure procmail
> 2.1 Suitable for accounts which ...
> 2.2 Where to put "pure procmail" UBE checks?
> 2.3 Using Procmail Module Library to fight spam
>
> 3.0 A heavyweight UBE blocking system
> 3.1 Advice for Debian Exim 4 mail system administrator
> 3.2 Advice for the normal account
> 3.3 Configuring Bayesian programs
> 3.4 A heavyweight spam catch setup using procmail
>
> Some terminology
>
> ._UBE_ = Unsolicited Bulk Email
> ._UCE_ = (subset of UBE) Unsolicited Commercial Email
>
> _Spam_ = Spam describes a particular kind of Usenet posting (and
> canned spiced ham), but is now often used to describe many kinds of
> inappropriate activities, including some email-related events. It
> is technically incorrect to use "spam" to describe email abuse,
> although attempting to correct the practice would amount to tilting
> at windmills.
>
> _Spam_ = definition by Erik Beckjord. "Some people decide that Spam
> is anything you decide you want to ban if you can't handle the
> intellectual load on a list." Remember, not to be confused with
> real spam, which is unwanted bulk mail.
>
> People are nowadays seeking a cure which will stop
> or handle UBE. That can be easily done with procmail (under your
> control) and with sendmail (by your sysadm). In order to select the
> right strategy against UBE messages, you should read this section
> and then decide how you will be using your procmail to deal with it.
>
>
AC
alanconnor
AT
earthlink
DOT net