RESOLUTION
SYMPTOMS:
Spamassassin cannot be managed through Plesk CP. If you try statrt it via Plesk CP the error occurs:
0: /opt/psa/admin/plib/common_func.php3:153
psaerror(string 'Unable to make action: Unable to manage service by spamd: Unable to start service.')
1: /opt/psa/admin/htdocs/server/restart_services.php:28
RESOLUTION:
1. Make sure that SpamAssassin is enabled in "/etc/default/spamassassin". There should be the lines:
# Change to one to enable spamd
ENABLED=1
2. Try to run "$PRODUCT_ROOT_D/admin/sbin/packagemng" utility to update Plesk components list in the database.
3. Restart SpamAssassin and Plesk.