This tutorial will show you how to install and use the Secured2 addin for Office 365, Outlook.com & Office 2016 Desktop.
Step 2. Once installed a blue S2 icon will appear in the ribbon / addin area of your email client. This may differ from Office 365 or Outlook.com depending on your version. Click on the addin area and you will see it. Once installed to secure an email beyond encryption all you need to do is click the S2 button, then the lock and the email is secured. Then hit send!