FortiMail units have two types of Bayesian databases:

All types contain Bayesian statistical data that can be used by Bayesian scans to detect spam, and should be trained in order to be most accurate for detecting spam within their respective scopes. For more information on training each type of Bayesian database, see “Training the Bayesian databases”.

Only one Bayesian database is used by any individual Bayesian scan; which type will be used depends on the directionality of the email and your configuration of the FortiMail unit’s protected domains and antispam profiles. For information, see “Use global Bayesian database”.