Hmmm your mail headers are missing the X-Spam stuff..
X-Spam-Checker-Version: SpamAssassin 3.1.7 (2006-10-05) on host.aabbccdd.info
X-Spam-Status: No, score=2.0 required=5.0 tests=AWL,DNS_FROM_RFC_ABUSE,
DNS_FROM_RFC_POST,HTML_MESSAGE autolearn=no version=3.1.7
Are you sure that Spamassassin is enabled?
re: Can anyone point me in the right direction?
For me (Debian Sarge) it's in /var/mail