Using the RelayCountry plugin
The [http://spamassassin.apache.org/full/3.0.x/dist/doc/Mail_SpamAssassin_Plugin_RelayCountry.html RelayCountry] plugin exposes the countries that a mail was relayed from – turn it on by reading that documentation page, installing the CPAN module required {cpan IP::Country::Fast
, and uncommenting the 'loadplugin' line in the /etc/mail/spamassassin/init.pre
file for Mail::SpamAssassin::Plugin::RelayCountry
.
The [http://spamassassin.apache.org/full/3.0.x/dist/doc/Mail_SpamAssassin_Plugin_RelayCountry.html RelayCountry] plugin will add metadata to the Bayesian filtering process, allowing the Bayesian filters to learn information based on countries.
When using SA 3.1.0, you can also write rules that match specific countries, e.g.:
header RELAYCOUNTRY_CN X-Relay-Countries =~ /CN/ describe RELAYCOUNTRY_CN Relayed through China score RELAYCOUNTRY_CN 3.0 header RELAYCOUNTRY_RU X-Relay-Countries =~ /RU/ describe RELAYCOUNTRY_RU Relayed through Russian Federation score RELAYCOUNTRY_RU 2.0
Also, you can apply a patch [http://bugzilla.spamassassin.org/show_bug.cgi?id=3815] which will allow you to add a separate MIME header that shows all the message's relay countries, independent of the rules.
add_header all Relay _RELAYCOUNTRY_
and this will show up in your MIME headers as:
X-Spam-Relay: US CN RU