I know that you said Spamassassin updates are handled via service packs but from the looks of things service packs aren't released all that often. I was wondering if it would be ok to manually update any of the rules that have updates since some are a bit dated.
For example, the currently installed 70_sare_stocks.cf has a modified date of 2006-10-18 while the one from rulesemporium.com was modified 2006-12-04.
include /usr/share/spamassassin/extra/70_sare_bayes_poison_nxm.cf
include /usr/share/spamassassin/extra/70_sare_evilnum0.cf
include /usr/share/spamassassin/extra/70_sare_genlsubj0.cf
include /usr/share/spamassassin/extra/70_sare_header.cf
include /usr/share/spamassassin/extra/70_sare_html.cf
include /usr/share/spamassassin/extra/70_sare_random.cf
include /usr/share/spamassassin/extra/70_sare_specific.cf
include /usr/share/spamassassin/extra/70_sare_spoof.cf
include /usr/share/spamassassin/extra/70_sare_stocks.cf
include /usr/share/spamassassin/extra/70_sare_unsub.cf
include /usr/share/spamassassin/extra/72_sare_bml_post25x.cf
include /usr/share/spamassassin/extra/72_sare_redirect_post3.0.0.cf
include /usr/share/spamassassin/extra/99_FVGT_Tripwire.cf
include /usr/share/spamassassin/extra/99_sare_fraud_post25x.cf
include /usr/share/spamassassin/extra/bogus-virus-warnings.cf
For example, the currently installed 70_sare_stocks.cf has a modified date of 2006-10-18 while the one from rulesemporium.com was modified 2006-12-04.
include /usr/share/spamassassin/extra/70_sare_bayes_poison_nxm.cf
include /usr/share/spamassassin/extra/70_sare_evilnum0.cf
include /usr/share/spamassassin/extra/70_sare_genlsubj0.cf
include /usr/share/spamassassin/extra/70_sare_header.cf
include /usr/share/spamassassin/extra/70_sare_html.cf
include /usr/share/spamassassin/extra/70_sare_random.cf
include /usr/share/spamassassin/extra/70_sare_specific.cf
include /usr/share/spamassassin/extra/70_sare_spoof.cf
include /usr/share/spamassassin/extra/70_sare_stocks.cf
include /usr/share/spamassassin/extra/70_sare_unsub.cf
include /usr/share/spamassassin/extra/72_sare_bml_post25x.cf
include /usr/share/spamassassin/extra/72_sare_redirect_post3.0.0.cf
include /usr/share/spamassassin/extra/99_FVGT_Tripwire.cf
include /usr/share/spamassassin/extra/99_sare_fraud_post25x.cf
include /usr/share/spamassassin/extra/bogus-virus-warnings.cf