# Customer.io: Reduced Deliverability to Microsoft-Hosted Email Addresses

> Message Sending has reduced deliverability to Microsoft-hosted email addresses. Customer.io reports that this issue is resolved. Microsoft resolved the underlying issue, and deliveries to Microsoft services return to normal.

- Provider: [Customer.io](https://outages.cc/customerio.md)
- Type: Incident
- State: resolved
- Worst impact: Operational
- Started: 2026-09-04 12:16 UTC
- Components: Message Sending
- Official update: https://stspg.io/zs381hpbdrrv

## Updates from Customer.io

### resolved, 2026-11-01 17:18 UTC

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.