To send a secure email in Microsoft Outlook, you can use email encryption methods such as S/MIME or Microsoft 365 Message Encryption (OME). Here is a step-by-step guide covering setup and sending encrypted emails:

Setting Up Email Encryption in Outlook

1. Choose Your Encryption Method

• S/MIME Encryption: Requires both sender and recipient to have digital certificates (digital IDs) installed that verify identities and enable encryption.
• Microsoft 365 Message Encryption (OME): Available for Microsoft 365 subscribers; does not require recipients to have certificates and supports features like "Do Not Forward" restrictions.

2. Obtain and Install a Digital Certificate (for S/MIME)

• Purchase or request a digital certificate from a trusted Certificate Authority (CA) such as Comodo, GlobalSign, or IdenTrust.
• Install the certificate in Outlook:
  • Go to File > Options > Trust Center > Trust Center Settings.
  • Select Email Security.
  • Under Encrypted Email , click Settings.
  • Choose your installed certificate under Certificates and Algorithms and confirm.

3. Configure Outlook for Encryption

• In the Trust Center Settings , under Email Security , ensure that encryption settings are enabled.
• Optionally, check Encrypt contents and attachments for outgoing messages to encrypt all outgoing emails by default.

Sending an Encrypted Email in Outlook

Using S/MIME Encryption

1. Open Outlook and click New Email.
2. Compose your message.
3. Go to the Options tab.
4. Click Encrypt and select the encryption option (e.g., Encrypt-Only).
5. Add recipients who have compatible certificates.
6. Click Send.

Using Microsoft 365 Message Encryption (OME)

1. Compose a new email in Outlook.
2. In the email window, go to the Options tab.
3. Click Encrypt and choose between options like Encrypt-Only or Do Not Forward.
4. Add recipients (they do not need certificates).
5. Send the email. Recipients receive a secure link to view the message.

Important Notes

• For S/MIME, both sender and recipient must exchange digital certificates to read encrypted emails.
• For OME, recipients can open encrypted emails via a secure web portal, even without Microsoft 365.
• Your Microsoft 365 subscription must support encryption features.
• Adding "[Secure]" in the subject line can prompt recipients to authenticate before viewing the email for added security.

This process ensures your emails are encrypted and only accessible to intended recipients, protecting sensitive information during transmission