Delayed Email Deliverability

Summary

Delayed Email Deliverability

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.

• Started

  Aug 14, 2026 · 8:24 PM

• Resolved

  Aug 16, 2026 · 6:04 PM

• Duration

  1d 21h 40m

• Severity

  Minor

• ◐

  Investigating

  Aug 14 · 8:24 PM WorkOS

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

• ◆

  Identified

  Aug 14 · 9:35 PM WorkOS

  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.

• ◉

  Monitoring

  Aug 14 · 11:32 PM WorkOS

  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.

• ◆

  Identified

  Aug 15 · 12:21 PM WorkOS

  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.

• ✓

  Resolved

  Aug 16 · 6:04 PM WorkOS

  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.