Does ZCS keep a per-user spam/ham bayes db?

If not, I'd like to make it do that. It gives much better results since it fine-tunes the token set each user is likely to get.

In our spamassassin frontend where we run spamd, I currently execute spamd like this:
/usr/sbin/spamd --create-prefs -u mailuser -x -l --max-children 5 --helper-home-dir --virtual-config-dir=/etc/spamassassin/userprefs/%l -d

This creates and uses per-virtual-user userprefs (including bayes dbs) in /etc/spamassassin/userprefs. I'm not yet sure how to make Zimbra do this. Maybe it invokes SA from amavisd.