As of October 16th 2026 13:30 UTC, Proofpoint restored Quarantine logic for Core Email Protection API to its previous state.
After working closely with Microsoft, we were able to restore this functionality and create Quarantine folders without failures. After monitoring for the past few hours without issue, we will now move this to resolved.
No components marked as affected
Resolved
As of October 16th 2026 13:30 UTC, Proofpoint restored Quarantine logic for Core Email Protection API to its previous state.
After working closely with Microsoft, we were able to restore this functionality and create Quarantine folders without failures. After monitoring for the past few hours without issue, we will now move this to resolved.
Monitoring
Starting October 7th 2026 at ~07:20 UTC Proofpoint began to receive Graph API failures when attempting to create a user's Quarantine folder for Core Email Protection API.
Impact: For less than 600 individual mailboxes in total across all customers and environments, this resulted in some emails failing to quarantine.
As of October 9th 2026 17:30 UTC all impacted messages have now been quarantined.
Remediation: As of October 9th 2026 16:48 UTC - To prevent broader impact, Proofpoint has pushed a change where all quarantined messages are moved to a hidden folder within the user's inbox. This is how quarantine for Core Email Protection API functioned up until July 2026. Although the user can't access this folder, if they go searching for a mail item it may show in the search results.
Proofpoint has escalated the issue to Microsoft to understand the initial cause. As impact is now remediated, we will only look to update the quarantine logic back once we are confident we will be able to create the required folder as expected and without error.
We will hold this page open in a monitoring state until we have a better understanding of the long term timeline.
Feel free to open a support case with any questions or concerns.
