If you have an LDAP directory server configured, you can configure Quarantine so that end users can access the messages in Quarantine and receive Quarantine notifications. Checking Enable Quarantine on the Spam Quarantine Settings tab enables quarantine globally, but you must still enable it for individual policy groups (including administrator policy groups) whose members you want to be able to access end-user quarantine.
The Enable Quarantine option is disabled by default if LDAP is not configured. In that case, this option is unchecked and grayed out.
You cannot enable end user quarantine either globally or locally unless you have configured a directory data source for BOTH Control Center Authentication AND Email Scanning AND enable end user quarantine for any custom policy group (i.e. any policy group other than the Default) to enable access to end user quarantine and quarantine notifications.