               SpamAssassin SNF4SA Plugin for SNFServer
                             README file

              Copyright (C) 2009 ARM Research Labs, LLC.

           See www.armresearch.com for the copyright terms.
                                   
This directory contains the SpamAssassin plugin for SNFServer.

The plugin implements a rule that checks the email message with
SNFServer.

If SNFServer determines that the email message is spam, then
SpamAssassin increments the score by an amount that depends on the
SNFServer result.  The amount to add for each SNFServer result is
specified in the configuration file.

The GBUdb scan result also changes the score by:

  abs(p * c) ^ 0.5 * sign(p) * MaxWeight

where p is the probability and c is the confidence returned by the
GBUdb scan, sign(p) is -1 if p < 0 and +1 otherwise, and MaxWeight is
specified in the configuration file.  If SNFServer is not configured
to insert the GBUdb scan results into a header in the message, or
MaxWeight is not specified in the configuration file, then the
SpamAssassin score is not affected by the GBUdb scan results.

In addition to scanning the message, the plugin inserts headers into
the email.  The SNFServer must be configured to insert the headers
into the email message.  The following headers are copied by the
plugin into the message if SNFServer is configured to generate them:

  1) 'X-SPAM-MessageSniffer-Scan-Result' contains the body of the
  X-MessageSniffer-Scan-Result header inserted by SNFServer.

  2) 'X-SPAM-MessageSniffer-Rules' contains the body of the
  X-MessageSniffer-Rules header inserted by SNFServer.

  3) 'X-SPAM-GBUdb-Analysis' contains the body of the X-GBUdb-Analysis
  header inserted by SNFServer.

Please see the INSTALL file for installation and configuration.
