If needed, set the message sensitivity level. Apart from Default, the two following options are available: Confidential and Personal. To mark an email, when creating an email, click the Message sensitivity button at the bottom of the new email composer and select the desired value from the drop-down list.
The corresponding information is displayed on the mini panel in the list of emails, as well as in the email body when the recipient opens the email and to the right of the date and time of the email.