It turns out that SpamAssassin is adding a score of 3.2 (FH_DATE_PAST_20XX) to all email going through my mail server (Mac OS X 10.6 Server) because of the above bug.
Jan 1 09:46:36 mail.example.com /usr/bin/amavisd: (25021-16) SPAM, <email@example.com> -> <firstname.lastname@example.org>, Yes, score=11.101 tag=2 tag2=6 kill=6 tests=[BAYES_99=3.5, FH_DATE_PAST_20XX=3.188, HTML_IMAGE_ONLY_32=1.778, HTML_IMAGE_RATIO_02=0.383, HTML_MESSAGE=0.001, MIME_HTML_ONLY=1.457, RDNS_NONE=0.1, SPF_FAIL=0.693, SPF_HELO_FAIL=0.001], autolearn=no, quarantine fydtn7Bx7ffD (email@example.com)
In the bug the rule is defined in
/rulesrc/sandbox/emailed/00_FVGT_File001.cf however this does not exist on Mac OS X - does any know where this rule is defined on Mac OS X Server? There are no files prepended with 00_ in
/usr/share/spamassassin/ which is where I assumed it would be.