How to encrypt email in Outlook in 2025

Encrypting emails in Outlook is essential for protecting sensitive information like financial documents, legal contracts, or confidential business communications. While standard Outlook uses TLS encryption during transmission, it doesn't provide end-to-end encryption or password protection for your email content by default. Understanding how to properly encrypt emails in Outlook helps you protect confidential information from unauthorized access.

Outlook offers several methods to enhance email security, from S/MIME encryption to Office 365 Message Encryption (OME). However, for highly sensitive documents, combining Outlook with secure file sharing platforms provides the strongest protection. This guide covers multiple approaches to sending encrypted emails in Outlook, helping you choose the right method for your security needs.

Quick recap of Outlook encryption methods

1. S/MIME encryption: End-to-end encryption using digital certificates for Outlook desktop
2. Office 365 Message Encryption (OME): Built-in encryption for Microsoft 365 users
3. Secure file sharing links: Share encrypted documents via secure links instead of attachments

Method 1: Using S/MIME encryption in Outlook

S/MIME (Secure/Multipurpose Internet Mail Extensions) provides true end-to-end encryption for Outlook, ensuring only the intended recipient can read your email.

Step-by-step guide for S/MIME encryption:

1. Obtain a digital certificate:

   • Purchase an S/MIME certificate from a trusted Certificate Authority (CA)
   • Popular providers include DigiCert, GlobalSign, or Sectigo
   • Install the certificate on your computer

2. Configure S/MIME in Outlook:

   • Open Outlook and go to File > Options
   • Click Trust Center > Trust Center Settings
   • Select Email Security
   • Under Encrypted email, click Settings
   • Choose your S/MIME certificate
   • Check "Encrypt contents and attachments for outgoing messages" if desired
   • Click OK to save settings

3. Compose an encrypted email:

   • Compose a new email in Outlook
   • Click the Options tab in the message ribbon
   • Click Encrypt or Encrypt-Only
   • A lock icon will appear in the message header
   • Write your email and send it

4. Verify encryption status:

   • The recipient must also have S/MIME configured
   • Both parties need valid digital certificates
   • Outlook will show encryption status in the message header

Important note: S/MIME requires both sender and recipient to have digital certificates installed. For recipients without S/MIME, consider using Office 365 Message Encryption or secure file sharing links instead.

Method 2: Using Office 365 Message Encryption (OME)

Office 365 Message Encryption provides encryption for Microsoft 365 users without requiring digital certificates.

Step-by-step guide for OME:

1. Verify OME availability:

   • OME is available for Microsoft 365 Business Premium, Enterprise E3, E5, or Office 365 Enterprise plans
   • Contact your IT administrator if OME isn't enabled

2. Compose an encrypted email:

   • Open Outlook and compose a new email
   • Click the Options tab
   • Click Encrypt or Encrypt-Only
   • For additional protection, select Do Not Forward to prevent forwarding

3. Send your encrypted email:

   • Write your message and add attachments
   • Click Send
   • Recipients will receive an encrypted email that opens in a secure web portal

4. Recipient experience:

   • Recipients receive an email with instructions to view the encrypted message
   • They click a link to open the message in a secure portal
   • No special software or certificates required for recipients

Benefits: OME works with any email address, not just Outlook users. Recipients can view encrypted emails through a web browser without additional setup.

Method 3: Sending encrypted files via secure links

Instead of attaching files directly to Outlook, you can share encrypted documents through secure links that provide stronger protection and tracking capabilities.

Step-by-step guide for secure file sharing:

1. Upload your file to a secure platform:
   • Use Papermark or another secure file sharing service
   • Upload your sensitive document
   • The file is automatically encrypted with AES-256 encryption

2. Configure security settings:
   • Enable password protection for the document
   • Set access expiration dates if needed
   • Enable email verification to require recipient identity confirmation
   • Configure allowlist/denylist to control who can access

3. Generate secure link:

   • Copy the secure document link from the platform
   • The link format typically looks like: https://www.papermark.com/view/[unique-id]

4. Compose your Outlook email:

   • Open Outlook and compose a new email
   • Paste the secure link in the email body
   • Write a message explaining what the link contains
   • Do not include the password in the email

5. Share password separately:

   • Send the password through a different channel:
     • Phone call
     • Text message
     • Encrypted messaging app (Signal, WhatsApp)
     • In-person communication

Benefits: This method provides stronger encryption than Outlook's built-in features, includes access tracking and analytics, and allows you to revoke access even after sending the email. Learn more about which files need encryption to determine when to use this approach.

Share encrypted files securely

Comparison: Outlook encryption methods

Best practices for encrypted Outlook emails

Follow these practices to maximize the security of your encrypted Outlook communications.

1. Use strong passwords: When using password protection with secure file sharing, create strong, unique passwords. Never reuse passwords across different files or accounts.

2. Share passwords separately: Always share passwords through a different channel than the email containing the link. Use phone calls, text messages, or encrypted messaging apps.

3. Enable two-factor authentication: Protect your Outlook account with two-factor authentication (2FA) to prevent unauthorized access to your email account.

4. Verify recipient identity: Before sending sensitive encrypted emails, verify the recipient's email address and identity to ensure you're sending to the correct person.

5. Use secure file sharing for sensitive documents: For highly sensitive files like financial documents or legal contracts, use secure file sharing platforms that provide encryption, access controls, and tracking capabilities.

6. Set appropriate expiration dates: Use expiration dates for time-sensitive information. Secure file sharing platforms offer expiration features, and OME supports message expiration.

7. Monitor access when possible: Use platforms that provide access analytics to track who viewed your encrypted files and when. This helps identify unauthorized access attempts.

8. Keep software updated: Ensure your Outlook app and any encryption tools are kept up to date with the latest security patches.

9. Combine encryption methods: For maximum security, combine email encryption with file encryption to protect both the message and attachments.

Conclusion

Encrypting emails in Outlook requires understanding the available options and their limitations. S/MIME provides true end-to-end encryption for users with digital certificates, while Office 365 Message Encryption offers convenient server-side encryption for Microsoft 365 users. For highly sensitive documents, combining Outlook with secure file sharing platforms provides the strongest protection with encryption, access controls, and detailed tracking capabilities.

Choose the encryption method that matches your security needs, and always follow best practices like sharing passwords separately and verifying recipient identities. For comprehensive file encryption with advanced security features, consider using platforms like Papermark that combine encryption with password protection, access controls, and detailed analytics.

Start sending encrypted emails securely

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