We are currently investigating an issue impacting some Core Email Protection API and AEDLP customers.

Update timeline

1. investigating May 29, 2026, 09:05 AM UTC

   Status: Investigating We are currently investigating an issue impacting some Core Email Protection API and AEDLP customers. Since 20:48 UTC 28th May 2026, a subset of mailboxes stopped syncing across some customers. A workaround was applied at 02:30 UTC May 29th and we are seeing impacted mailboxes connecting again. We are continuing to work to restore full functionality. The team is working diligently and with urgency on full remediation. Affected components Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance) Core Email Protection API (Degraded performance)

2. identified May 29, 2026, 03:09 PM UTC

   Status: Identified Proofpoint has identified the cause, and continues to work on a resolution for impacted customers. For full details of the impact, please consult here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 We will continue to update on the progress of resolution via this page and the community article. Affected components Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance) Core Email Protection API (Degraded performance)

3. identified May 29, 2026, 06:26 PM UTC

   Status: Identified By May 29 2026 - 14:00 UTC, Proofpoint Engineering deployed a potential fix and have been monitoring the results. We have now started to see slow recovery across the impacted customer base. We will continue to monitor and explore options to speed recovery. At this stage in recovery we do not yet have an expected timeline, but will continue to evaluate and provide one as able. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance) Core Email Protection API (Degraded performance)

4. identified May 29, 2026, 09:01 PM UTC

   Status: Identified Proofpoint Engineering continues to deploy incremental fixes to speed up recovery, however progress continues slowly. At this time we still do not have an expected timeline, but cross functional teams continue to actively explore all avenues available until we achieve a full recovery. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance) Core Email Protection API (Degraded performance)

5. identified May 30, 2026, 01:32 AM UTC

   Status: Identified Proofpoint Engineering continues to monitor recovery and aide in efforts, in addition to continued optimization, we have engaged 3rd party vendor support to accelerate recovery where relevant. At this time we still do not have an expected timeline, but cross functional teams continue to actively explore all avenues available until we achieve a full recovery. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance)

6. identified May 30, 2026, 09:59 AM UTC

   Status: Identified Proofpoint Engineering remains engaged with 3rd party vendor support and is actively monitoring recovery. At this time we still do not have an expected timeline, but cross functional teams continue to actively explore all avenues available until we achieve a full recovery. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components M365 Add-in (Degraded performance) Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance)

7. identified May 30, 2026, 05:16 PM UTC

   Status: Identified Proofpoint Engineering identified additional steps to speed up recovery, and has seen positive results after testing and deploying. As of right now, we tentatively estimate the last of impacted mailboxes to recover after 00:00 UTC June 1st, in the early morning hours. As we progress, we will update accordingly. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance)

8. identified May 31, 2026, 01:48 AM UTC

   Status: Identified Proofpoint Engineering continues to monitor recovery, and it remains on track. As of right now, we tentatively estimate the last of impacted mailboxes to recover after 00:00 UTC June 1st, in the early morning hours. As we progress, we will update accordingly. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance)

9. identified May 31, 2026, 01:51 PM UTC

   Status: Identified Proofpoint Engineering continues to monitor an on track recovery, making adjustments as needed. As of right now, we tentatively estimate the last of impacted mailboxes to recover after 00:00 UTC June 1st, in the early morning hours. As we progress, we will update accordingly. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance)

10. identified May 31, 2026, 07:13 PM UTC

    Status: Identified Proofpoint Engineering continues to monitor as we approach recovery for all mailboxes. As of right now, we tentatively estimate the last of impacted mailboxes to recover after 00:00 UTC June 1st, in the early morning hours. As we progress, we will update accordingly. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance) Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance)

11. identified Jun 01, 2026, 02:02 AM UTC

    Status: Identified At this time, the majority of customers and mailboxes have recovered. For a small number of customers, individual mailboxes remain disconnected, and Proofpoint Engineering is investigating each. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Core Email Protection API (Degraded performance) Proofpoint Cloud Email Security Platform (Degraded performance) Core Email Protection API (Degraded performance) M365 Add-in (Degraded performance)

12. monitoring Jun 01, 2026, 12:10 PM UTC

    Status: Monitoring Proofpoint Engineering continued to investigate the remaining individual mailboxes overnight, and as of 01-June-2026 07:30 UTC all mailboxes impacted by this Service Interruption are resolved. Proofpoint continues to work on post incident activities and monitoring. As incident is now stable, no further updates will be provided and we will move this to resolved after 24 hours. We'd encourage you to open a Support Case if you have any additional questions or concerns. You can read the full impact per product, here: https://proofpoint.my.site.com/community/s/article/Proofpoint-Service-Interruption-Affecting-Core-Email-Protection-API-Protection-29-May-2026 Affected components Proofpoint Cloud Email Security Platform (Operational) Core Email Protection API (Operational) M365 Add-in (Operational) Core Email Protection API (Operational)

13. resolved Jun 02, 2026, 02:46 PM UTC

    Status: Resolved All systems remain stable, and Proofpoint continues to work on post incident activities and monitoring. We'd encourage you to open a Support Case if you have any additional questions or concerns. Affected components Proofpoint Cloud Email Security Platform (Operational) Core Email Protection API (Operational) M365 Add-in (Operational) Core Email Protection API (Operational)