Delayed Email Deliverability

What to do

• Check whether you use WorkOS AuthKit. Check your stack

  Paste a package.json, lockfile, Terraform or a list of domains at down.guide/stack to see every provider you depend on.

• Confirm your retries, queues and scheduled jobs caught up after the 1d 20h it lasted.

  Anything that failed between 2026-08-15 01:35 UTC and 2026-08-16 22:04 UTC may need a replay.

• Subscribe to WorkOS's feed to hear about the next one first. RSS feed

  https://down.guide/feed?provider=workos works in Slack (/feed subscribe), Discord feed bots and any RSS reader.

Updates from WorkOS 5

1. investigatingAug 15, 2026, 12:24 AM UTC

   We are seeing deliverability issues with emails sent to Microsoft / Outlook recipients.

   provider

2. identifiedAug 15, 2026, 1:35 AM UTC

   We continue to experience deliverability delays to a subset of users with email addresses hosted by Microsoft / Office 365. We are working with our email providers to mitigate the issues, we will provide updates as they become available. Customers using their own custom email providers are not affected.

   provider

3. monitoringAug 15, 2026, 3:32 AM UTC

   We are observing improvements in deliverability to Microsoft email addresses, in line with the resolution of an incident with our upstream email service provider. We will continue to monitor.

   provider

4. identifiedAug 15, 2026, 4:21 PM UTC

   We continue to see email deliverability issues to a subset of Microsoft 365 tenant domains. This does not affect consumer domains such as outlook.com, hotmail.com, live.com or msn.com. We will provide updates as they become available.

   provider

5. resolvedAug 16, 2026, 10:04 PM UTC

   Microsoft's Outlook team has confirmed that mitigations have been implemented. We've verified that email delivery to Microsoft 365 domains is operating normally again. This incident has been resolved.

   provider

Corrections

None so far.

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