spam filtering system

[Kyle Babich]

I have my spam prefrences set on aggresive. Any messages marked as spam get filtered to a special folder and messages marked as high spam get silently rejected. Generally everything works fine but how do messages like the below get to my inbox from time to time? It scored 7.5, it should be in the spam folder like all of the others, so why isn't it?

Return-Path: <km5xvbf87aiz@whs.btrd.ab.ca>
Received: from server3.fastmail.fm (server3.internal [10.202.2.134])
by server2.fastmail.fm (Cyrus v2.1.9) with LMTP; Sun, 29 Jun 2003 09:18:23 -0400
X-Sieve: CMU Sieve 2.2
Received: from smtp.us.messagingengine.com (server3.internal [10.202.2.134])
by server3.fastmail.fm (Cyrus v2.1.9) with LMTP; Sun, 29 Jun 2003 09:18:23 -0400
Received: from smtp.us.messagingengine.com (localhost [127.0.0.1])
by server3.messagingengine.com (Postfix) with ESMTP
id 52461920EA; Sun, 29 Jun 2003 09:18:22 -0400 (EDT)
Received: from 127.0.0.1 ([127.0.0.1] helo=smtp.us.messagingengine.com) by messagingengine.com
with SMTP; Sun, 29 Jun 2003 09:18:22 -0400
X-Mail-from: km5xvbf87aiz@whs.btrd.ab.ca
X-Spam-score: 7.5
Received: from 66.111.4.4 (unknown [61.173.43.30])
by smtp.us.messagingengine.com (Postfix) with SMTP
id 7B900924B0; Sun, 29 Jun 2003 09:18:18 -0400 (EDT)
Received: from ([157.61.107.36]) by 66.111.4.4; Sun, 29 Jun 2003 18:10:09 +0200
Message-ID: <gru$--4z678ql-ua7u5e3x93-f4881@vwsa.2.vl>
From: "Bryce Osborne" <km5xvbf87aiz@whs.btrd.ab.ca>
To: some-address-that-is-not-mine@myfastmail.com
Subject: RE: Your Check dc z ubecgk
Date: Sun, 29 Jun 03 18:10:09 GMT
X-Mailer: Internet Mail Service (5.5.2650.21)
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary=".F3.2860DC73C_"
X-Priority: 3
X-MSMail-Priority: Normal

[Si1]

If mail is sent to more than one Fastmail user, the most conservative threshold setting out of that group of users is used to filter the mail.