How to Encrypt Emails in Outlook

Encrypting an email is a form of cryptographically securing it so no one apart from the intended recipients will be able to read it. When you encrypt an email, the readable message is transformed into scrambled code only deciphered by authorized recipients.

Outlook offers two methods of encrypting an email, namely:

  • Microsoft 365 Message Encryption: This method is native to Office 365 subscribers with an Enterprise E3 license and doesn’t require additional setup.
  • S/MIME encryption: This method requires acquiring a digital certificate from your IT admin, adding it to your computer, then configuring Outlook to use this certificate.

This guide will go through the steps in encrypting an email using Microsoft 365 in the Outlook desktop and web apps. Make sure you have an Office 365 with an Enterprise E3 license since this feature is not applicable to other users without a subscription.

Sending Encrypted Emails on Outlook Desktop

  1. Create a new email on your Outlook desktop by clicking New Email.

    New Email Button in Outlook Desktop
    Select New Email.
  2. Compose your email as you usually would.

    Email With Body and Recipients
    Write your email.
  3. Go to the Options tab.

    Options Tab in New Email Window
    Click on the Options tab.
  4. On the top ribbon, click on the lock icon in “Encrypt” to encrypt your email. You can also click on the small arrow-down┬áto select other ways to encrypt your message.
    • Encrypt-Only: encrypts the email, but recipients are not limited to how they use it.
    • Do Not Forward: prevents recipients from forwarding, printing, and copying the content of the email.
    • Confidential \ All Employees: This prevents recipients from forwarding, printing, and copying the email’s content and prevents you from sending the email to contacts outside your organization.
    • Highly Confidential \ All Employees: prevents recipients from forwarding, printing, copying the email’s content, or replying to the email and prevents you from sending the email to contacts outside your organization.Encrypt Drop-Down Menu Under OptionsSelect an encryption option.
  5. After choosing an encryption option, you will see a label on top of the email notifying you that the email is encrypted.
    Label on Encrypted Email
    Your encrypted email will now have a label on top.

    If you’re ready to send the email, click Send.

    Send Button on Encrypted Email
    Hit Send.

Opening an Encrypted Email in the Outlook Desktop App

For Microsoft 365 or outlook.com Users

Users receiving the encrypted email can open and read it as usual. The main difference is it will have markings showing it’s encrypted.

Encrypted Email in Recipient's Inbox
A lock icon to the email’s right.
Opened Encrypted Email
Encrypt Only notification.

For Non-Microsoft Users (gmail.com, yahoo.com, etc.)

  1. Launch the Outlook desktop app and click on the encrypted email. Instead of a lock icon, it will have an attachment icon (even if the sender didn’t include any attachments in the email).

    Encrypted Email in Non-Microsoft User's Inbox
    Select the encrypted email.
  2. To read the email, click Read the message on the email body. This will launch a browser window.

    Read the Message Button in Encrypted Email
    Click on the Read the Message button.
  3. You can sign in with your provider (e.g., Google) or with a one-time passcode sent to your email.

    Sign In Window in Browser
    Sign in using your preferred method.
  4. After signing in, you can view the email.

    Encrypted Email Viewed in Browser
    Encrypted email is now displayed.

Sending Encrypted Emails on Outlook Web

  1. Sign in to outlook.com and create a new email by clicking New message.

    New Message Button in Outlook Web App
    Hit New Message.
  2. Write your email as usual.

    Composed Email in Outlook Web
    Compose your email.
  3. Select the Encrypt button above the “To” field.

    Encrypt Button on Outlook Web
    Click on Encrypt.
  4. To change the encryption type, click on Change permissions.

    Change Permissions Button in Outlook Web
    Click on Change permissions.
  5. In the drop-down menu, select how you want to encrypt your message. Then, click OK.
    Encryption Options Drop-Down Menu
    Choose from the encryption option.

    OK Button in Change Permissions Dialog Box
    Hit OK.
  6. Once you’re ready, hit Send.

    Send Button in Outlook Web
    Click Send.

Opening an Encrypted Email via Browser

For Microsoft 365 or outlook.com Users

  1. Sign in to outlook.com and open the email with a lock icon on the far-right side.

    Encrypted Email in Outlook Web
    Open the encrypted email.
  2. The email will open as usual, but it will display a label on top informing you of the encryption type used.

    Opened Encrypted Email in Outlook Web
    Encrypted email is viewed as usual.

For Non-Microsoft Users (gmail.com, yahoo.com, etc.)

  1. Sign in to your email account on your browser. Then, open the encrypted email.

    Encrypted Email in Gmail
    Open the encrypted email in your browser.
  2. Click on Read the message. This will open another tab.

    Read the Message Button in Encrypted Email in Gmail
    Click on Read the message.
  3. Sign in to view the message (with your provider like Google or using a One-time passcode).

    Sign In Window for Encrypted Message
    Sign in with your preferred method.
  4. Once you’re signed in, you can read the email.

    Opened Encrypted Email in Browser
    Encrypted email is opened in the new tab.

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