ZEN TECHWORKS - has created a method to send 'encrypted email'. Just follow the instructions below.
How do I send an encrypted email?
From any email program: To encrypt an email using Bracket simply open your favorite email program, and send an email as you normally would. All you have to do is wrap your subject in brackets [like this] before you send your message. When you wrap your subject line in brackets it will tell our systems to encrypt the message and will automatically sent notifications to the recipients you have defined.
From bracket.email: You can also create and send an encrypted email when you're signed in to bracket.email. Just click the pencil icon in the left navigation bar to create a new message. If you’re on your smartphone just tap the button in the bottom right of your inbox. When you create a new message directly from the Bracket portal, you'll notice that brackets wrap your subject automatically, so there’s no need to add them manually.
New messages and replies are automatically saved as a draft. If something happens to your computer or device while you're creating a message don’t worry - it will simply show up in your inbox as a draft which you can open and finish any time.