Encrypt email messages
- S/MIME encrypted – Sender and receiver must use a mail program that supports S/MIME. Outlook supports the S/MIME Standard
- Microsoft 365 Message Encryption (Information Rights Management – To use Microsoft 365 Message Encryption, the sender must own Microsoft 365 Message Encryption which is included with the Office 365 Enterprise E3 license.
Updates to email encryption and a new Encrypt button
Outlook now offers better email encryption with the Office update
The new Encrypt button offers both S/MIME encryption and IRM. Only Outlook users with a S/MIME certificate can see the S/MIME option.
You can find detailed instructions for adding encryption in Encrypting using S/MIME and Encrypt with Microsoft 365 Message Encryption.
Before you can begin this process, you need to have added a certificate to your keychain. After you have the signing certificate on your computer, configure it in Outlook.
- Select Options > Trust Center > Trust Center Setting from the File menu.
- Select Email Security in the left pane.
- Choose Settings under Encrypted Email.
- Click on Certificates and Algorithms to select the S/MIME certification.
- Select OK
Insider with Microsoft 365 subscription, here’s what is new to you:
Choose Options in an email message and select Encrypt. Then, from the drop-down, choose Encrypt with S/MIME.
If you have a S/MIME Certificate installed on your computer, you’ll see the Encrypt with S/MIME.
For Outlook 2019 & Outlook 2016
Choose Options and Permissions in an email message
After you have finished writing your email, choose to Send it.
Encrypt your messages with Microsoft 365 Message Encryption
Here’s what you can do if you are a Microsoft 365 subscriber:
Select Options in an email message and select Encrypt. Choose the encryption that has the restrictions that you wish to enforce such as Encrypt Only or Do Not Forward.
Note: Microsoft 365 Message encryption is included in the Office 365 Enterprise E3 license. Encrypt-Only (the option under Encrypt button) can only be enabled for subscribers (Microsoft 365 apps for enterprise users) who also use Exchange Online.
Outlook 2019 and 2016
Select Options > Permissions in an email message and choose the encryption option with the restrictions you want to enforce.
Encrypt one message
- Click File > Properties in the message you are currently composing.
- Click Security Settings and select Encrypt attachments and message contents checkbox.
- Write your message and click Send.
All outgoing messages should be encrypted
Encrypting all outgoing messages by default allows you to write and send messages as usual, but any potential recipients will need your digital ID in order to decode or view the messages.
- The File tab. Choose Options > Trust Center > Trust Center Settings.
- Under Encrypted Email, click on the Security tab. Select the Encrypt contents or attachments for the outgoing mail check box.
- Click Settings to modify additional settings, like choosing a certificate to use.