I don't pretend to understand this stuff, but here is some of the header info from a typical spam from today's flood:
Received: from adminteam ([203.123.157.82]) by na3sys009amx187.postini.com ([74.125.148.10]) with SMTP;
Mon, 01 Apr 2013 10:47:16 CDT
Received: (qmail 3351 by uid 143); Mon, 1 Apr 2013 15:48:00 -0530
From: "No risk Katy Perry Free trials" <[email protected]>
To: <[email protected]>
Subject: Fwd: ..
Date: Mon, 1 Apr 2013 15:19:48 -0530
Message-ID: <005301ce2f1e$7ff59b90$7fe0d2b0$@com>
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0052_01CE2F1E.7FF59B90"
X-Mailer: Microsoft Office Outlook 12.0
Thread-Index: Acjhs69UR3NtbvBhPNkurEv2AtSBlw==
Content-Language: en-us
X-pstn-levels: (S: 0.00000/66.47495 CV:99.9000 FC:95.5390 LC:95.5390 R:95.9108 P:95.9108 M:97.0282 C:98.6951 )
X-pstn-dkim: 0 skipped:not-enabled
X-pstn-status: off
X-Bayes-Prob: 0.0001 (Score 0, tokens from: @@RPTN)
X-Spam-Score: 2.00 (**) [Tag at 3.80] HK_NAME_FREE,HTML_MESSAGE,SPF(none:0),RBL(rp-grey:1.0)
X-CanIt-Geo: ip=203.123.157.82; country=IN; region=25; city=Chennai; latitude=13.0833; longitude=80.2833; http://maps.google.com/maps?q=13.0833,80.2833&z=6
X-CanItPRO-Stream: 06202139 (inherits from 32_HI_TAG-LO_BLOCK,default)
X-Canit-Stats-ID: Bayes signature not available
X-Scanned-By: IEEE Spam Scanner (https://uce.ieee.org/) on 140.98.193.228
While here is some typical "legitimate" spam (that gets flagged by my mail forwarder):
From: "The New Yorker" <[email protected]>
To: <[email protected]>
Subject: ***[Possible UCE]*** =?utf-8?B?QXByaWwgOCwgMjAxMzogSGVucnkgQmxvZGdldDsgdGhlIHJpc2Ugb2YgVmljZSBNZWRpYTsgY29va2luZyBzaG93czsgYW5kIG1vcmUu?=
Date: Mon, 01 Apr 2013 22:31:44 +1000
MIME-Version: 1.0
X-Mailer: MailEnable
X-Priority: 3
Message-ID: <40efcf1c-741e-4e4e-b0ce-90fd5b422bc3.MAI@mail.realviewtechnologies.com>
Content-Type: multipart/alternative;
boundary="--=_NextPart_01042013103144_006229358"
X-RVID: 101536031
X-pstn-neptune: 28/1/0.04/98
X-pstn-levels: (S:30.17530/99.90000 CV:99.9000 FC:95.5390 LC:95.5390 R:95.9108 P:95.9108 M:97.0282 C:98.6951 )
X-pstn-dkim: 0 skipped:not-enabled
X-pstn-status: off
X-Bayes-Prob: 0.9919 (Score 2.5, tokens from: @@RPTN)
X-Spam-Flag: YES
X-Spam-Score: 4.00 (****) [Tag at 3.80] HTML_MESSAGE,SPF(softfail:0),RBL(rp-mixed:1.5),Bayes(0.9919:2.5)
X-CanIt-Geo: ip=210.87.32.100; country=AU; region=07; city=Melbourne; latitude=-37.8139; longitude=144.9634; http://maps.google.com/maps?q=-37.8139,144.9634&z=6
X-CanItPRO-Stream: 06202139 (inherits from 32_HI_TAG-LO_BLOCK,default)
X-Canit-Stats-ID: Bayes signature not available
X-Scanned-By: IEEE Spam Scanner (https://uce.ieee.org/) on 140.98.193.228
It's curious that the spam score of this second is twice that of the first, and the Bayes probability (whatever that is) is near certainty, while for the first case it's essentially nil. Seems like somehow the first case was successfully eluding the spam filter.
(For what it's worth, the flood seems to have stopped.)