SMTP Log Entry

I found this log entry and don’t know what this means;

08/25/2004 10:49:14 AM SMTP Server: localhost (203.210.210.81) connected

The IP is not one of ours. Wondering if why is this using a ‘localhost’ and not the usual ‘Remote Host’ entry. This connection btw, is denied by DNSBL.

Thanks in advance for any thoughts.

Roel