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plugin announcement: FCrDNS

From:
Matt Simerson
Date:
April 26, 2013 08:26
Subject:
plugin announcement: FCrDNS
Message ID:
2EE7376D-F010-4FFC-A9E9-4931318F7053@tnpi.net

NAME
       Forward Confirmed RDNS - http://en.wikipedia.org/wiki/FCrDNS

DESCRIPTION
       Determine if the SMTP sender has matching forward and reverse DNS.

       Sets the connection note fcrdns.

WHY IT WORKS
       The reverse DNS of zombie PCs is out of the spam operators control.
       Their only way to pass this test is to limit themselves to hosts with
       matching forward and reverse DNS. At present, this presents a
       significant hurdle.


There's more POD that explains the tests, config settings, and method. 

Much like many other plugins, fcrdns is not reliable enough (only about 90%)  to use for message rejection. However, when combined with any sort of heuristics system such as the karma plugin, the fcrdns plugin provides another extremely reliable indication of spam likelihood. 

Matt


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