1. Check if mail handlers exist on your server:
# /usr/local/psa/admin/sbin/mail_handlers_control --list
2. Examine the mail log to see if the mail handlers are executed:
# tail /usr/local/psa/var/log/maillog | grep qmail-queue-handlers
3. Run mchk to regenerate mail handlers:
# /usr/local/psa/admin/sbin/mchk --with-spam