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MC383875: Microsoft Defender for Office 365: Quarantined message storage in hidden system folder on user mailbox

Updated December 2, 2022: We have updated the rollout timeline below. Thank you for your patience.

Updated October 5, 2022: We have updated the rollout timeline below. Thank you for your patience.

Updated August 2, 2022: We have updated the content below for clarity. Thank you for your feedback.

Updated June 7, 2022: We have updated the content below for clarity. Thank you for your feedback.

Updated May 24, 2022: We have updated this message to show as intended. Thank you for your feedback.

Microsoft Defender for Office 365 is making some changes to quarantine folder storage. The experience for users will remain the same and users can leverage the delete action to maintain the storage folder for their quarantined messages. This message is associated with Microsoft 365 Roadmap ID 93302.

MC383875: Microsoft Defender for Office 365: Quarantined message storage in hidden system folder on user mailbox

When this will happen

  • Standard: will begin rolling out in mid-June and be completed by mid-November (previously mid-September). – Complete
  • Government: will begin rolling out in mid-January 2023 (previously mid-November 2022) and be completed by early April 2023 (previously late November 2022).

How this will affect your organization

Non delivery report (NDR):

In the case that a user’s quarantine storage is full, new incoming messages routed to quarantine will be rejected and an NDR will be generated for those messages.

In the case of Zero hour Auto Purge, where malicious items need to be zapped from inbox to quarantine but there is no space, these messages will be instead, added to the junk mail folder.

Note: When there is a False positive Zero hour Auto Purge, messages wrongly moved to the Junk mail folder can be added back to their original location.

New hard delete experience:

Previously, when messages were deleted by users from quarantine, those deleted messages could still be retrievable within a 30-day period after deletion was made. To help users better manage their storage, we will be introducing a hard delete experience whereby once the messages are hard deleted, they can’t be recovered.

To help users better manage their storage, we will be introducing a hard delete experience whereby once the messages are hard deleted, they can’t be recovered.

Note: End users will only be able to delete quarantine messages that their Administrators has given them access to through the quarantine policy.

What you need to do to prepare

The goal for this communication is mostly for informational awareness. You may consider updating your training and documentation as appropriate.

Learn more

Message ID: MC383875
Published: 23 May 2022
Updated: 02 December 2022
Platform: Online, US Instances, Web, World tenant

Alex Lim is a certified IT Technical Support Architect with over 15 years of experience in designing, implementing, and troubleshooting complex IT systems and networks. He has worked for leading IT companies, such as Microsoft, IBM, and Cisco, providing technical support and solutions to clients across various industries and sectors. Alex has a bachelor’s degree in computer science from the National University of Singapore and a master’s degree in information security from the Massachusetts Institute of Technology. He is also the author of several best-selling books on IT technical support, such as The IT Technical Support Handbook and Troubleshooting IT Systems and Networks. Alex lives in Bandar, Johore, Malaysia with his wife and two chilrdren. You can reach him at [email protected] or follow him on Website | Twitter | Facebook

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