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📖 What is Microsoft 365 Message Encryption (OME)?

Microsoft 365 Message Encryption (OME) is a feature that allows users to send encrypted emails to both internal and external recipients. It ensures that sensitive information remains protected during transit and is only accessible by authorized, authenticated users.

🥋 Sensei Says:

"Know the difference between the 'Encrypt' and 'Do Not Forward' options when sending sensitive mail to external parties."

📚 Certification: Microsoft 365 Administrator (MS-102)

🔑 What are the Key Concepts of Microsoft 365 Message Encryption (OME)?

  • Distinguish between 'Encrypt' and 'Do Not Forward' options; the latter prevents recipients from forwarding, printing, or copying the content of the email.
  • External recipients without Microsoft accounts can access encrypted messages using a one-time passcode (OTP) or by authenticating with a supported third-party provider.
  • Integration with Microsoft Purview allows administrators to apply encryption automatically via sensitivity labels based on the classification of the content.
  • Mail flow rules in the Exchange Admin Center can be configured to trigger OME based on specific keywords, sender, or recipient attributes.
  • OME ensures end-to-end protection by encrypting the message at rest and during transit, requiring authentication before the content is decrypted.

🎯 How does Microsoft 365 Message Encryption (OME) appear on the MS-102 Exam?

You may be asked to determine the best encryption setting for a scenario where a HR manager sends a salary offer to a candidate and must prevent the email from being forwarded.

A scenario might describe a requirement to automatically encrypt all outbound emails sent to a specific partner domain; you will need to identify the correct mail flow rule configuration.

Expect questions regarding the recipient experience for non-Microsoft users, specifically how the one-time passcode (OTP) process allows secure access to encrypted messages without requiring a full Microsoft account.

❓ Frequently Asked Questions

How does OME differ from using a Sensitivity Label?

OME is the actual encryption technology used to protect the message. Sensitivity Labels are a classification tool that can be configured to automatically apply OME settings when a specific label is selected.


Can an administrator revoke access to an encrypted email after it has been sent?

Yes, if the message was sent using OME, the sender or a global administrator can revoke access to the message, which effectively prevents the recipient from viewing the content.

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