This incident has been resolved. Microsoft has restored its email services, and validation for Microsoft-hosted addresses (Outlook, Hotmail, Live, MSN and Microsoft 365) is back to normal processing times. Warmup and Inbox Placement Tester results are also back to normal.
If you received “unknown” validation results for Microsoft addresses during the incident, we recommend re-validating them. If you ran Inbox Placement tests during this period, re-run them for accurate Microsoft placement data.
Non-Microsoft providers were not affected at any point. Thank you for your patience.
Posted Nov 14, 2026 - 00:05 PST
Monitoring
Microsoft reports broad recovery across its email services, and we’re seeing errors for Microsoft-hosted addresses drop significantly. Validation is returning to normal processing times.
Because Microsoft is still clearing a backlog of delayed messages (held for up to 48 hours), warmup activity and Inbox Placement Tester results involving Outlook, Hotmail, Live, MSN and Microsoft 365 inboxes may continue to show late or incomplete deliveries for a while. For accurate Microsoft placement data, we recommend re-running tests once this incident is marked resolved.
All other email providers remain unaffected. We’ll post a final update once Microsoft confirms full resolution.
Posted Nov 13, 2026 - 12:02 PST
Update
We’re tracking Microsoft’s progress and will post an update as soon as we see recovery.
Posted Nov 13, 2026 - 03:52 PST
Identified
We’re aware of an ongoing Microsoft service disruption affecting their mail infrastructure. Validation requests for Microsoft-hosted addresses (e.g. Outlook, Hotmail, Live, MSN and Microsoft 365 business domains) may take longer than usual to process, and some may temporarily return as “unknown.”
All other email providers are unaffected, and our platform is fully operational. Validation, scoring and API services for non-Microsoft addresses continue to run normally.
Warmup activity involving Microsoft inboxes may also see delays until the disruption is resolved.
Inbox Placement Tester: Results for Microsoft seed inboxes (Outlook, Hotmail, Microsoft 365) may be delayed or temporarily incomplete. Placement results for Gmail, Yahoo and other providers are not affected. If you need full Microsoft results, we recommend re-running the test once the disruption is resolved.
No action is needed on your end. We’re monitoring Microsoft’s status and will post an update once their service is restored. For time-sensitive lists, we recommend re-validating any “unknown” Microsoft results after the incident is resolved.
Posted Nov 13, 2026 - 03:51 PST
This incident affected: API, API-US, API-EU, and Bulk API.