Enabling mailbox quotas Support for mailbox quotas is enabled and disabled through the MailSite Console. To enable mailbox quotas: 1. Open the MailSite Console 2. Click on the Server folder 3. Double-click the "Quotas" icon 4. Select the "Enable quota support" check box 5. Save the change Once Quota support is enabled, set the mailbox quota level for each domain through the Domain Properties window.