To send encrypted email in Outlook, you have two main options: using S/MIME encryption or Microsoft Purview Message Encryption (OME). Here is how to do it:
Using Microsoft Purview Message Encryption (OME) in Outlook (New Outlook
and Microsoft 365)
- Compose a new email message.
- Go to the Options tab in the message window.
- Click Encrypt.
- Choose the encryption option you want, such as Encrypt (encrypt only) or Do Not Forward (which also prevents forwarding).
- Finish composing your email and click Send.
Recipients will receive a message indicating it is encrypted and may need to verify their identity by signing in or using a one-time passcode to view the email
Using S/MIME Encryption in Classic Outlook
Setup (one-time):
- Obtain a digital ID (certificate) from a trusted Certificate Authority (e.g., Comodo, GlobalSign).
- Import the certificate into Outlook via File > Options > Trust Center > Trust Center Settings > Email Security > Import/Export.
- Share your digital certificate with your recipients by sending them a digitally signed email.
Sending an encrypted email:
- Create a new email.
- Go to Options > Encrypt.
- Select the desired encryption option (e.g., Encrypt with S/MIME).
- Compose and send your email.
Note that all recipients must have your digital ID to decrypt the message, and they need to share their certificates with you to send encrypted replies
Additional Notes
- You can configure Outlook to encrypt all outgoing messages by default via File > Options > Trust Center > Trust Center Settings > Email Security, then check Encrypt contents and attachments for outgoing messages.
- S/MIME encrypts the message content and attachments but not the subject line.
- Microsoft Purview Message Encryption is easier to use for recipients without certificates, as it uses identity verification methods like one-time passcodes.
- Outlook Web App (OWA) also supports sending encrypted emails via the Encrypt button when composing a new message
In summary, for most users, the easiest way to send encrypted emails in Outlook is to use the built-in Encrypt option under the Options tab when composing a message, which uses Microsoft Purview Message Encryption. For organizations requiring stronger certificate-based encryption, S/MIME can be set up but requires more configuration and certificate management.
