Sounds like you are either being probed by a SPAMMER using a spoofed address or a internal system is trying to send email to the Filtering server. The 192.168.1.0 address space is a non routable address space reserved for internal networks like. This is why the country is unknown.

You need to make sure that you don't have an internal system trying to send an email through your filtering server. Your internal systems should be using your outgoing mail server not the SpamFilter server.

This looks similar to the Country: N/A that I see in our logs as each email is being processed. We also use a non-routable address space behind a firewall. The way that I read this is that the country of origin is being determined from the IP address from which the email most immediately arrives. Am I right/wrong? Does this mean that the country filters will not work behind firewalls / in non-routable address spaces? If so, is there a work around for this (other than placing SpamFilter on a maching outside the firewall...!)?

Robert