Spam Assassin is giving above 7.0 score. The key reason being SPF failure. Here is a SPAM Assassin header:
"Yes, hits=7.33 required=5.00
tests=MIME_HTML_ONLY,HTML_MESSAGE,HTML_TAG_EXISTS_TBODY,EXCUSE_1,SPF_FAIL,MR_NOT_ATTRIBUTED_IP,SARE_FROM_SPAM_WORD3,NO_RDNS2
autolearn=Yes version=3.0"