in e-smith-email there's a "purge_junkmail" script (check in /etc/cron.d)
it runs /etc/e-smith/events/actions/purge-junkmail-folders
so, AFAIK, purging emails is already available..
regarding "blacklisting".. AFAIK you can only tell SA to "learn" about spam.. search wiki and forums about "spamassassin bayesan learning"