The following is a list of tests that we run against the E-mails arriving at the spamtraps, and what percentage of the spam they caught (it may be easier to read if you use a fixed-width font):
WEIGHT10 99.61% WEIGHT20 97.42% NOLEGITCONTENT 96.41% SPAMMANAGER 95.50% SNIFFER 94.72% SPAMCHK 93.17% IPNOTINMX 90.25% XBL 78.22% SPAMCOP 75.06% MAILDEFLECTOR 61.37% EASYNET-DNSBL 55.72% DSBLALL 47.88% DSBL 47.19% BADHEADERS 46.86% BLARSBL 39.82% FIVETENSRC 37.70% EASYNET-PROXIES 35.97% EASYNET-DYNA 34.49% REVDNS 31.98% EXPER 31.74% FREEMAIL 31.51% NJABLPROXIES 31.35% NOPOSTMASTER 30.67% HELO 29.71% NOABUSE 28.83% ROUTING 21.11% RSL 19.61% SPAMHAUS 18.85% BLITZEDALL 14.85% SPAMHEADERS 14.82% COMMENTS 13.14% BASE64 12.96% IPWHOIS 10.60% DSN 9.71% COMPU 9.28% DELINK 7.64% NJABLSOURCES 6.71% FABELSOURCES 5.10% NJABLDUL 4.97% INTERSIL 4.69% SPAMBAG 4.06% FIVETENIGNORE 3.72% LNGSDUL 3.71% BADWHOIS 3.01% NJABL 2.80% FIVETENOPTIN 2.46% VOX 2.36% ORDB 2.21% MAILFROM 1.86% KUNDENSERVER 1.60% LNGSBLOCK 1.03% PIGS 0.85% DSBLMULTI 0.68% DNSRBL-DUN 0.60% JIPPG-DUL 0.53% NONENGLISH 0.53% DEVNULL 0.34% KITHRUP 0.29% FIVETENMULTI 0.07% FIVETENOTHER 0.02% DNSMAILLIST 0.01% JIPPG-DULJP 0.01%
The WEIGHT10 and WEIGHT20 tests are a weighting system that assigns a weight to each E-mail, based on the spam tests that fail, so they don't really count as spam tests by themselves (but, they show that you can catch as much as 97-99+% of spam with extremely few false positives). It is also important to note that different tests are more likely to produce false positives (such as the IPNOTINMX, XBL, REVDNS, and SPAMHEADERS tests, that all catch a lot of spam, but catch a lot of legitimate mail as well); those tests need to be used in a weighting system, so E-mail will only be marked as spam if it fails a combination of tests. The NOLEGITCONTENT and IPNOTINMX tests were designed to help identify legitimate E-mail (rather than spam), which accounts for their high percentages.
It is interesting to note that at least 46% of the spam in September could safely be caught by the BADHEADERS test (since no RFC-compliant mail client will send out E-mail that fails the BADHEADERS test).
There are 3 spam tests that catch over 90% of the spam in our spamtraps: SPAMMANAGER ( http://www.spammanager.com ), SNIFFER ( http://www.sortmonster.com ), and SPAMCHK ( http://www.riedmann.it/spamchk/ ) (at its strictest setting; normally, a less strict setting would be used, to minimize false positives).
More information on most of the spam tests shown above can be found at http://www.declude.com/junkmail/support/ip4r.htm . You can look up an IP address using the Spam Database Lookup tool at http://www.DNSstuff.com to see what spam databases it is listed in. The most recent 20 spams in our spamtraps, and the tests they failed, can be found at http://www.declude.com/spamtrap.htm .
-Scott
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