In some rare cases, the on disk rules by Symantec Messaging Gateway for Service Providers (SMG-SP) may become corrupted or unreadable by the SMG-SP Brightmail Engine (bmserver) and will need to be reset to the default rule set that shipped with the software.
cd /opt/symantec/smg-sp/Scanner
service mailwall stop
rm -rf bm_ruleset.*
cp -rp etc/bm_ruleset.2.* .
service mailwall start