SpamTitan uses policies to decide how mail is treated. Policies can be applied to a domain (domain policy) or a user (user policy). By default, users inherit the policy set for their domain. However, a user-level policy can be created that overrides the domain-level policy.
User policies are useful to customize a user's settings. For example, if the domain policy for example.com specifies that quarantine reports are sent every weekday, a user policy for email@example.com could override this so their quarantine report is only delivered weekly.
Go to Filtering > Domain Policies or User Policies to configure policies. User level policies are only available at the domain level.