Reduced Deliverability to Microsoft-Hosted Email Addresses

Summary

Reduced Deliverability to Microsoft-Hosted Email Addresses

Microsoft has resolved the underlying issue, we are seeing deliveries to their services resume as normal. Earlier bounces will be retried accordingly. We appreciate your understanding and please do reach out to support if you need any further assistance.

• Started

  Sep 4, 2026 · 12:16 PM

• Resolved

  Sep 4, 2026 · 1:35 PM

• Duration

  1h 19m

• Severity

  None

• ◐

  Investigating

  Sep 4 · 12:16 PM Customer.io

  We are currently investigating reports of reduced deliverability affecting messages sent to Microsoft-hosted email addresses. Our team is actively looking into this and we will provide an update as soon as we have more information. Thank you for your patience!

• ◉

  Monitoring

  Sep 4 · 12:30 PM Customer.io

  Starting around 08:00 UTC, Microsoft began experiencing an incident causing an increased volume of deferred/bounced emails. We are actively monitoring the situation. No other email providers are currently affected.

• ✓

  Resolved

  Sep 4 · 1:35 PM Customer.io

  Microsoft has resolved the underlying issue, we are seeing deliveries to their services resume as normal. Earlier bounces will be retried accordingly. We appreciate your understanding and please do reach out to support if you need any further assistance.