Outage in Clerk
Delayed email delivery to Microsoft (Outlook / Microsoft 365) recipients
Resolved Minor
September 04, 2026 - Started 5 days ago
- Lasted about 5 hours
Incident Report
Summary AI Generated
Clerk experienced a 4.6-hour incident where emails to Microsoft-hosted mailboxes (Outlook.com, Hotmail, Microsoft 365) were delayed due to rate limiting on Microsoft's receiving end, a issue affecting multiple senders industry-wide. One-time passcodes and verification links were most impacted, with delays of several minutes, while emails to all other providers delivered normally. Delivery returned to normal around 12:40 UTC, with all delayed emails subsequently delivered.
We are seeing delays in email delivery for recipients on Microsoft-hosted mailboxes (Outlook.com, Hotmail, Microsoft 365). Affected emails, including one-time passcodes and verification links, may arrive late or require re-sending. Emails to other providers are delivering normally. We are working with our email provider to restore normal delivery.
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Latest Updates ( sorted recent to last )
MONITORING
5 days ago - at 09/04/2026 01:33PM
Delivery to Microsoft-hosted mailboxes returned to normal at about 12:40 UTC and delayed emails have been delivered. We are monitoring to confirm it stays that way.
IDENTIFIED
5 days ago - at 09/04/2026 11:37AM
We've found the cause. Emails to Microsoft-hosted mailboxes (Outlook.com, Hotmail, Microsoft 365) are being rate limited on the receiving side, and other email senders are seeing the same thing today. Emails are still accepted but some are delayed by several minutes while they're retried. Emails to all other providers are delivering normally. We're monitoring and will update when delivery times return to normal. If a code hasn't arrived, requesting a new one is the fastest workaround.
INVESTIGATING
5 days ago - at 09/04/2026 10:06AM
We are seeing delays in email delivery for recipients on Microsoft-hosted mailboxes (Outlook.com, Hotmail, Microsoft 365). Affected emails, including one-time passcodes and verification links, may arrive late or require re-sending. Emails to other providers are delivering normally. We are working with our email provider to restore normal delivery.
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