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How to Keep Sensitivity Labels Applied on External Emails
Question details
The user wants to know how to ensure sensitivity labels remain applied when sending subsequent replies in an external email thread.
- Product
- Exchange Online
- Device & OS
- not provided
- Scenario
- Replying back and forth in an email chain involving external recipients where data protection labels are required.
- Observed behavior
- Sensitivity labels are retained on the first reply but drop off and must be manually reapplied on subsequent replies, which is the current by-design behavior in Exchange Online.
Verify your current Microsoft Purview Information Protection policies and ensure you have the appropriate permissions to assign sensitivity labels in your email client.
Manually Reapply the Sensitivity Label Before Sending
Since automatically retaining the label on subsequent external replies is currently unsupported by design in Exchange Online, the primary workaround is to manually reapply the label.
Microsoft Exchange Online does not currently support the automatic retention of sensitivity labels across multiple reply iterations with external recipients. To ensure your data remains protected, users must develop a habit of verifying and reapplying the label during the drafting phase of subsequent replies.
In your Outlook client or Outlook on the web, hit 'Reply' or 'Reply All' to the external email thread.
Navigate to the 'Message' tab on the top ribbon and locate the 'Sensitivity' button.
Click the 'Sensitivity' button and select the correct data protection label from the drop-down menu.
Ensure the label is visibly applied to the email header or information bar, then click 'Send'.
Submit Feedback to the Exchange Online Community
Inform Microsoft about the impact of this limitation on your workflow to encourage future feature updates.
Try WPS Office for Secure Document Management
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- 1. Download the installer: Visit the official WPS Office website and click the free download button for your operating system.
- 2. Install the software: Run the downloaded installation file and follow the quick on-screen instructions.
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Frequently Asked Questions
Why do sensitivity labels disappear on subsequent replies?
This is a confirmed by-design behavior in Microsoft Exchange Online. While the label is retained on the initial reply to an external email, the system does not automatically carry it forward to further replies in the same thread, requiring users to manually reapply it.
Can mail flow rules automatically apply sensitivity labels?
Yes, Exchange administrators can configure mail flow (transport) rules in the Exchange admin center to automatically apply specific Microsoft Purview sensitivity labels to emails sent to external domains, which can act as a fallback for users forgetting to manually label their replies.
Will a sensitivity label applied to an email protect its attachments?
This depends on the specific label's configuration in the Microsoft Purview compliance portal. Administrators can set policies so that applying a label to an email also applies the same level of encryption or restrictions to supported attached documents.
