woman encrypting an email in outlook
3 min

How To Encrypt An Email In Outlook

Email is not always secure. Messages can be intercepted or manipulated at multiple points in their journey from sender to recipient. Encrypting your emails can help to protect your privacy and security by reducing the chance of interception. Here's how to encrypt an email in Outlook.

Microsoft Outlook provides simple encryption types that enable users to protect their emails in transit. Let’s take a look at how to encrypt an email in Outlook using the most common method (S/MIME).

S/MIME encryption is a widely used protocol for encrypting email communications in transit.

How To Encrypt An Email In Outlook

To encrypt your email in Outlook, you will need to create a digital certificate.

A digital certificate is like a passport for the internet. It proves who you are and allows you to do things like send encrypted emails and access websites that require security.

Both sender and recipient must have a valid certificate linked to their email account to use S/MIME encryption.

Step 1: Set Up A Digital ID In Outlook

Before you can enable S/MIME encryption in Outlook, you’ll need to create and set up a digital ID certificate within Outlook.

If you don’t already have a Digital ID created, Microsoft recommends some popular Digital ID service providers.

Your organisation will have specific policies on the use of digital IDs and certificates, so if in doubt, contact your network administrator.

Once you have downloaded your Digital ID certificate, you'll need to add it to your Outlook client:

  1. Open Outlook and click on the ‘File’ tab. Set up Digital ID in Outlook - Step 1
  2. Select ‘Options’ at the bottom left of the menu. Set up Digital ID in Outlook - Step 2
  3. Click ‘Trust Center’ on the left-hand side.
  4. Press the ‘Trust Center Settings’ button. Set up Digital ID in Outlook - Step 3 and 4
  5. Click the ‘Email Security’ option in the menu on the left.
  6. Press the ‘Settings" button under the ‘Encrypted email’ section. Set up Digital ID in Outlook - Step 5 and 6
  7. In the ‘Security Settings Name’ field, give your settings a name.
  8. Under the ‘Certificates and Algorithms’ section, click ‘Choose’ to specify the digital ID you wish to use. Set up Digital ID in Outlook - Step 7 and 8

Step 2: Enable S/MIME Encryption In Outlook

Now that you have created your Digital ID, you can set up S/MIME encryption in Outlook. Simply follow these steps:

  1. Return to Outlook and click ‘File’ in the menu bar. Enable S_MIME encryption in Outlook - Step 1
  2. Select ‘Options’ and click on ‘Trust Center.’ Enable S_MIME encryption in Outlook - Step 2
  3. Within the Trust Center, choose ‘Trust Center Settings.’ 
    Enable S_MIME encryption in Outlook - Step 3
  4. Click the ‘Email Security’ option in the menu on the left.
  5. Check the box next to ‘Encrypt contents and attachments for outgoing messages’.
  6.  Click ‘OK’ to save your settings. Enable S_MIME encryption in Outlook - Step 4, 5, 6

Step 3: Send An Encrypted Email

With S/MIME encryption enabled in Outlook, you can now compose and send an encrypted email:

  1. Open Outlook and click ‘New Email’ to create a new message. Sending an encrypted email - Step 1
  2. Compose your email as you normally would, adding the recipient(s), subject, and message content.
  3. To encrypt the email, click on the ‘Options’ tab, found in the ribbon at the top of the email composition window. Sending an encrypted email - Step 3
  4. Within the ‘Options’ tab, click on ‘Encrypt’ in the ‘Permission’ group. You can then set the message to be sent with encryption only or with a no-forwarding rule. Sending an encrypted email - Step 4
  5. When this is completed, a message will appear above the ‘To’ field, indicating that the message will be encrypted when it is sent. Sending an encrypted email - Step 5
  6. Once you have finished composing the email, click ‘Send’ to transmit the encrypted message.

Step 4: Decrypt An Encrypted Email

When you or your recipient receives an encrypted email, Outlook will automatically decrypt it for you. All you need to do is:

  1. Open the encrypted email you received in your Outlook inbox.
  2. Outlook will automatically decrypt the message and display it.
  3. Read the decrypted email as you would any regular email.
Note: if you have an E3 or E5 Microsoft 365 plan, you may have access to Microsoft’s more advanced secure email method, Microsoft Purview Message Encryption. You can learn more about Microsoft Purview Message Encryption in our Microsoft 365 secure email vs Mailock review.

Securing Highly Sensitive Emails In Outlook

Encrypting your emails is a simple way to protect your personal privacy. However, encryption is not enough to secure highly sensitive information against all threats, and Microsoft advisers against using even its more advanced encryption methods as a security barrier.

If you’re looking for a solution designed to secure sensitive business information, you will need to consider more robust solutions.

There are several secure email solutions on the market that offer more advanced, more widely compatible protections for your sensitive communications, including our own solution, Mailock.

Our Mailock Outlook add-in brings additional security capabilities to your Outlook email client, including:

  • Recipient authentication
  • Compatibility with all email clients
  • Complete audit trails
  • Email revoke


Originally posted on 02 06 23
Last updated on December 21, 2023

Posted by: Sabrina McClune

Sabrina McClune is an expert researcher with an MA in Digital Marketing. She was a finalist in the Women In Tech Awards 2022. Sabrina has worked extensively with B2B technology companies conducting and compiling thorough academically driven research to produce online and offline media. She loves to read fantasy novels and collect special edition books.

Return to listing