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

> Customer.io reports reduced deliverability to Microsoft-hosted email addresses. This affects Message Sending. Customer.io states that Microsoft resolved the underlying issue and deliveries are normal again. Customer.io also states that earlier bounces will be retried.

- Provider: [Customer.io](https://outages.live/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 20:03 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.