There is an overview of the SPAM Blocking process here.
Client Geolocation
Detect geographic location of clients
Enable geolocation detection of client IP addresses. This identifies the likely geographic location of connecting client IP addresses and can thereby be used to weight, block or delete email originating from specific countries.
Use this to weight block or delete email from countries from which it is unlikely you receive legitimate email
On/Off
on
Client IP sender mismatch
If the sender e mail address mismatches the email sending IP location you can choose to mark, weight, block or delete the email
You may not wish to block some IPs or IP ranges regardless of the country in which they are based. For example, you should not block Hexamail IP ranges.
82.117.36.*
Geolocation
Click the countries on the map to weight email originating from the selected country. Click again to block, and once more to delete. Click a final time to clear the setting for the specified country.