Change that to zen.spamhaus.org and you should get better results.
Also, our /etc/rulesdujour/config file looks like this:
#
# Configuration File for Updating SpamAssassin with the
# Rules Du Jour Script /usr/local/sbin/rules_du_jour.
# Script is run once a day via cron and will update
# spamassassin rule sets by adding the third-party
# rule sets listed below. See
http://www.exit0.us/index.php?pagename=RulesDuJour
# for more information
#
# Version 1.00 - 2005-11-28 - L. Mark Stone - Initial configuration.
# Version 1.01 - 2006-10-11 - L. Mark Stone - Modified for use with Zimbra.
TRUSTED_RULESETS="TRIPWIRE SARE_BML SARE_FRAUD SARE_OEM SARE_STOCKS SARE_BAYES_POISON_NXM SARE_EVILNUMBERS0 SARE_EVILNUMBERS1 SARE_REDIRECT_POST300 SARE_HTML0 SARE_HTML1 SARE_HTML_ENG SARE_HEADER0 SARE_HEADER1 SARE_SPECIFIC SARE_ADULT SARE_GENLSUBJ0 SARE_GENLSUBJ1 SARE_UNSUB SARE_URI0 SARE_URI1 SARE_OBFU0 SARE_OBFU1 SARE_SPOOF SARE_RANDOM"
SA_DIR="/opt/zimbra/conf/spamassassin"
RULES_DU_JOUR_SCRIPT="/usr/sbin/rules_du_jour"
MAIL_ADDRESS="Use_Your_Own_Address@Your_Own_Domain .com"
SA_RESTART="/opt/zimbra/bin/zmamavisdctl restart"
SA_LINT=" "
Hope that helps.
All the best,
Mark