Administrator_Guide/en-US
Jeroen van Meeuwen
vanmeeuwen at kolabsys.com
Mon Dec 26 15:20:31 CET 2011
Administrator_Guide/en-US/Combating_Spam.xml | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
New commits:
commit 41b4a0fb88a9abec1b86fa3657284b89317ab54d
Author: Jeroen van Meeuwen (Kolab Systems) <vanmeeuwen at kolabsys.com>
Date: Mon Dec 26 15:20:09 2011 +0100
Extend chapter Combating Spam with the BAYES_99 score notes
diff --git a/Administrator_Guide/en-US/Combating_Spam.xml b/Administrator_Guide/en-US/Combating_Spam.xml
index f984a54..8c5f0c1 100644
--- a/Administrator_Guide/en-US/Combating_Spam.xml
+++ b/Administrator_Guide/en-US/Combating_Spam.xml
@@ -236,6 +236,30 @@
</section>
+ <section id="sect-Administrator_Guide-Combating_Spam-Tweaking_Bayes_Scores">
+ <title>Tweaking Bayes' Scores</title>
+ <para>
+ Bayes' score is dependent on the probability Bayes attaches of a message being spam. The rules used to match a message's probability of being spam are systematically prefixed with <literal>BAYES_</literal>, followed by the percentage of likelihood of the message being spam.
+ </para>
+ <para>
+ Because there is rarely a 100% certainty of a message being spam, the highest percentage is 99%. By default, the configuration attaches a 3.5 score to this probability. Depending on the configuration value for <literal>$sa_tag2_level_deflt</literal> supplied in the Amavis configuration file, <literal>6.31</literal> by default, it is unlikely spam will reach the cut-off point of actually being marked as spam solely on the basis of Bayes' probability score.
+ </para>
+ <para>
+ It is therefor recommended to increase the score attached to messages with a 99% probability of being spam to at least <literal>6.308</literal>, if not simply <literal>6.31</literal>. Using <literal>6.308</literal>, you configure spam to be tagged not solely on the basis of Bayes' 99% probability score, but request that in addition the message is recognized to be in HTML (and HTML only), and perhaps uses a big font –or similar patterns with a very small <literal>0.01</literal> score.
+ </para>
+ <procedure>
+ <title>Adjusting the Score for <literal>BAYES_99</literal></title>
+ <step>
+ <para>
+ Edit <filename>/etc/mail/spamassassin/local.cf</filename>, and make sure the following line is present:
+ </para>
+ <para>
+ <screen>score BAYES_99 6.308</screen>
+ </para>
+ </step>
+ </procedure>
+ </section>
+
<section id="sect-Administrator_Guide-Combating_Spam-Learning_about_Ham">
<title>Learning about Ham</title>
<para>
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