SpamAssassin Plugin: FreeMail
The FreeMail plugin checks the headers for indication that sender's domain is that of a site offering free email services.
Activation
The FreeMail module is activated by default on 3.3 installs.
loadplugin Mail::SpamAssassin::Plugin::FreeMail
Documentation
Generated documentation for the module is not available.
Configuration information is contained within the plugin code FreeMail.pm
The default list freemail domains is 20_freemail_domains.cf