Delays Processing Some Inbound and Outbound Emails

Proofpoint investigated elevated error rates processing inbound and outbound emails on our US Server. On June 12 2026 from 14:30 UTC to 16:19 UTC, ~2% of emails sent or received failed to process. Proofpoint Engineering have remediated the issue, and is currently monitoring. For Core Email Protection API - this mean impacted inbound emails were not initially submitted for scoring, did not create a security event, and could not be found in Investigation & Respond. Missed emails are currently being re-submitted, effectively translating to a delay in processing and remediation where applicable. For Adaptive Email DLP - this means reporting for M365 add-in user responses may be temporarily inaccurate on the timeline of a security event. A small percentage of checks done by the M365 Add-in quickly timed out and failed open during the impact window. For customers using the Gateway, these check would have been routed to and completed by the Gateway.