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- Path: senator-bedfellow.mit.edu!bloom-beacon.mit.edu!newsfeed.stanford.edu!news.killfile.org!not-for-mail
- From: tskirvin@killfile.org (Tim Skirvin)
- Newsgroups: news.admin.net-abuse.bulletins,news.admin.net-abuse.usenet,news.admin.net-abuse.sightings,news.admin.net-abuse.misc,news.answers
- Subject: FAQ: Current Usenet spam thresholds and guidelines
- Supersedes: <spam-faq.20040509050002$29fd@news.killfile.org>
- Followup-To: news.admin.net-abuse.usenet
- Date: Sun, 16 May 2004 00:00:01 -0500
- Organization: Killfiles, Unlimited
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- Summary: This posting contains the current Spam definitions, thresholds,
- and guidelines, as used by most major spam cancellers and news
- administrators.
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-
- Archive-name: usenet/spam-faq
- Posting-Frequency: weekly
- Last-modified: 1998/11/10
- URL: http://www.killfile.org/faqs/spam.html
- Maintainer: tskirvin@killfile.org (Tim Skirvin)
- Original-Author: clewis@ferret.ocunix.on.ca (Chris Lewis)
-
- Current Spam thresholds and guidelines.
-
- This article is intended to describe the current consensus spam thresholds
- and ensure that the definitions of these terms are available and consistent.
- It is believed that most, if not all, spam cancellers use these terms and
- definitions in their work; however, many other people use the terms
- inappropriately, which leads to confusion in discussions. This is an
- informal FAQ aimed at clarity and understanding, not anal-retentive
- correctness.
-
- Excessive Multi-Posting (EMP) has the same meaning as the term "spam"
- usually carries, but it is more accurate and self-explanatory. EMP means,
- essentially, "too many separate copies of a substantively identical
- article."
-
- "Substantively identical" means that the material in each article is
- sufficiently similar to construe the same message. The signature is
- included in the determination. These are examples of substantively
- identical articles:
-
- - byte-for-byte identical messages
- - otherwise identical postings minimally customized for
- each group it appears in.
- - advertising the same service.
- - articles that consist solely of the same signature
- - articles which consist of inclusions of other user's
- postings, but are otherwise identical.
-
- Cross-posting means that a single message appears in more than one group.
- Most newsreaders allow you to specify more than one group in a posting.
-
- Excessive Crossposting (ECP) refers to where a "lot" of postings to more
- than one group each have been made.
-
- Some people think cross-posting is "bad". In and of itself, it's good
- behaviour - it allows you to reach more groups with less impact on the net.
- Especially if you set the Followup-to: header to one group. It is "bad"
- when it's done to attack newsgroups or provoke flamewars (like cross-posting
- how to cook a cat between alt.tasteless and rec.pet.cats), but this is beyond
- the scope of this FAQ.
-
- This author considers the term "spam" to mean excessive postings of
- EMP and/or ECP variety. That is, "spam", is a generic term for several
- different things. The term was originally supposed to mean EMPs only, but
- most people use "spam" to mean "any excessive posting".
-
- A spam, EMP, or ECP therefore refers to a posting that has been posted to
- many places. There is a consensus that there is a point at which it is
- abuse, and is subject to advisory cancellation.
-
- A formula has been invented by Seth Breidbart which attempts to
- quantify the degree of "badness" of a spam (whether EMP or ECP) as a
- single number. The Breidbart Index (BI) is defined as the sum of the
- square roots of n (n is the number of newsgroups each copy was posted
- to).
-
- Example: If two copies of a posting are made, one to 9 groups, and one
- to 16, the BI index is sqrt(9)+sqrt(16) = 3+4 = 7.
-
- The BI2 (Breidbart Index, version 2) is an experimental metric, which
- may eventually replace the BI. It is calculated by computing the sum
- of the square roots of n, plus the sum of n, and dividing by two. Eg:
- one posting to 9, and one to 16 is
-
- (sqrt(9) + sqrt(16) + 9 + 16) / 2
- ( 3 + 4 + 9 + 16 ) / 2 = 32 / 2 = 16
-
- The BI2 is more "aggressive" than the BI, intended to cut off the "higher
- end". BI allows about 125 newsgroups maximum. BI2 allows a maximum of 35.
-
- A slightly less aggressive index is the SBI (Skirvin-Breidbart Index); it
- is calculated much the same as the BI2, but sums the number of groups in
- the Followup-to: header (if available), rather than the newsgroups. Eg:
- one posting to 9 groups, and one to 16 with followups set to 4 is
-
- (sqrt(9) + sqrt(16) + 9 + 4) / 2
- ( 3 + 4 + 9 + 4 ) / 2 = 20 / 2 = 10
-
- Except in nl.*, where the SBI is followed, the BI2 and SBI are not used to
- determine whether a spam is cancellable.
-
- The thresholds for spam cancels are based _only_ on one or more of the
- following measures:
-
- 1) The BI is 20 or greater over a 45 day period.
- 2) is a continuation of a previous EMP/ECP, within a 45 day
- sliding window. That is: if the articles posted within the
- past 45 days exceeds a BI threshold of 20, it gets removed,
- unless the originator has made a clear and obvious effort to
- cease spamming (which includes an undertaking to do so
- posted in news.admin.net-abuse.usenet). This includes "make
- money fast" schemes which passed the EMP/ECP thresholds
- several years ago. This author recommends one posting
- cross-posted to no more than 10 groups, no more often than
- once every two weeks (a BI of 3).
-
- A single posting cannot be cancellable - to reach a BI of 20, it would
- have to be cross-posted to 400 groups. This isn't possible due to
- limitations in Usenet software.
-
- These thresholds nominally apply to all hierarchies - not just the Big-8
- and alt.*. Many hierarchies have more restrictive rules, which are decided
- upon and enforced by their users and administrators; they may also opt out
- of the cancellations, at the discretion of the same users and admins.
-
- These cancels have nothing whatsoever to do with the contents of the
- message. It doesn't matter if it's an advertisement, it doesn't matter if
- it's abusive, it doesn't matter whether it's on-topic in the groups it was
- posted in, it doesn't matter whether the posting is for a "good cause" or
- not - spam is cancelled regardless, based on _how many times_ it was said
- and not _what_ was said.
-
- Administrators wishing to ignore spam cancels can "alias out" the site
- "cyberspam", and the cancels will not affect your system. This is normally
- done at your feed site, but patches are available for INN to allow you to
- reject spam cancels on your own system. Ask in news.admin.net-abuse.usenet
- if you need this patch.
-
- Further literature on posting etiquette and related information:
-
- The newsgroup news.announce.newusers
- <URL:news:news.announce.newusers>
-
- "What is Usenet", by Salzenberg, Spafford and Moraes
- <URL:ftp://ftp.faqs.org/faqs/usenet/what-is/part1>
-
- "What is Usenet? A second opinion.", by Vielmetti
- <URL:ftp://ftp.faqs.org/faqs/usenet/what-is/part2>
-
- "FAQ: Advertising on Usenet: How To Do It, How Not To Do It", by Furr
- <URL:ftp://ftp.faqs.org/faqs/usenet/advertising/how-to/part1>
-
- "A Primer on How to Work With the Usenet Community", by Von Rospach, et al
- <URL:ftp://ftp.faqs.org/faqs/usenet/primer/part1>
-
- "Rules for posting to Usenet", by Horton, Spafford & Moraes.
- <URL:ftp://ftp.faqs.org/faqs/usenet/posting-rules/part1>
-
- "Emily Postnews Answers Your Questions on Netiquette", by Templeton et al
- <URL:ftp://ftp.faqs.org/faqs/usenet/emily-postnews/part1>
-
- Numerous books and publications on Usenet, such as O'Reilly's "Stopping
- Spam" (Schwartz and Garfinkel), the "Whole Internet Guide and Catalog"
- (Krol), "Usenet Handbook" (Harrison), etc.
-
- "Cancel Messages: Frequently Asked Questions", by Skirvin
- <URL:http://www.killfile.org/faqs/cancel.html>
-
- The above FAQs are also mirrored at various sites, including as ftp.sunet.se,
- mirror.aol.com, ftp.uu.net, ftp.uni-paderborn.de, nctuccca.edu.tw,
- hwarang.postech.ac.kr, ftp.hk.super.net etc.
-
- A mailing list has been set up to assist those wishing to post commercial
- advertisements on Usenet in a responsible fashion. Email your questions to
- commerce@acpub.duke.edu.
-