How to enable email encryption in Office 365


  • Applies to: Administrator
  • Difficulty: Moderate
  • Time Needed: Approximately 30 minutes
  • Tools Needed: Office 365® Global Administrator access, Azure® Information Protection Plan 1 or 2

For more information about prerequisite terminology, see Cloud Office support terminology.

This article lists the steps to enable Office Message Encryption (OME) through the use of an Exchange Transport Rule. Administrators can set conditions that automatically encrypt emails.

Note: All users must have Azure Information Protection Plan 1 or 2 licenses for encryption to work.

Create the encryption transport rule

  1. Log in to your Office 365 Control Panel.

  2. From the left menu, select Office 365 Admin Center.

  3. From the left menu, select Exchange under Admin centers.

  4. Select mail flow from the left menu, then select rules from the top menu.

  5. Select + and then Create a new rule.... A pop-up window displays.

  6. In the pop-up window, name your rule by using the Name: field.

  7. Select More options... at the bottom of the page.

  8. Under Apply this rule if... select the conditions that must be met to apply encryption to an email message.

    Note: This option is customizable based on how you want to send out encrypted email. The following is a list of recommended conditions:

    • To encrypt all messages, use The Sender is… “Internal”.
    • Encrypt messages sent to specific domains by using the “The Recipient Address Includes…” condition and adding those domains.
    • Encrypt messages with a keyword by using the “The Subject or Body Includes…” condition and then select the words which you would like to encrypt a message automatically.
  9. Under Do the following... choose Modify the message security..., and then Apply Office 365 Message Encryption and rights protection.

  10. Select Encrypt from the RMS template options, and then click OK.

  11. Select Save.

Messages that meet the specified criteria now have OME applied to them when you send them.

Additional resources

To learn more about OME, see Office 365 Message Encryption.

To learn more about applying OME by using Exchange transport rules, see Define mail flow rules to encrypt email messages in Office 365.