Follow the appropriate instructions below depending upon whether you are using the Outlook desktop program for Windows or using the Outlook web app in a browser like Chrom, Edge, or Firefox. In order for these options to appear, you must have a Microsoft Exchange email account that supports encryption.
Microsoft Outlook for Windows
Create a new message.
Click "Options" at the top of the message and then click the Encrypt toolbar icon.
Microsoft Outlook Web Application
Create a new message. On the message toolbar, click "More Options" (three dots), then click Encrypt, and then click Encrypt just to the right of the first Encrypt.