Answer
Purchasing Plesk extension allows enabling a limited amount of various Spam Experts services:
- Incoming email filtering
- Outgoing email filtering
- Email archiving
Extension doesn't come with spam filters by default, only provides means to enable them. Filters must be purchased separately.
Filters can be purchased from Plesk directly or other Spam Experts distributor, like Openprovider.
Extension can be configured to work with a Spam Experts provider of one's choosing.
Instructions to configure extension for use with Openprovider
