# Mailjet: Microsoft Incident Resulting in Delivery Issues to M365

- Impact (vendor’s label): none
- Status: resolved
- Started: 2026-09-04 12:23 UTC · Resolved: 2026-09-04 12:55 UTC · Duration: 32 min
- Updates: 2
- [Vendor status page: https://stspg.io/mn9fk6lf3d6r](https://stspg.io/mn9fk6lf3d6r)
- [Company: Mailjet](https://rewindex.com/company/mailjet.md)

## Timeline of updates

- **monitoring** 2026-09-04 12:23 UTC: Starting around 08:00 UTC, Microsoft began experiencing an incident causing an increased volume of deferred emails across all M365 regions. The affected responses are returning "451 4.7.500 Server busy". Our teams are actively monitoring the situation. Sending to other email providers is not affected.
- **resolved** 2026-09-04 12:55 UTC: This incident has been resolved.


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Canonical: https://rewindex.com/company/mailjet/incidents/6cp6q10lvckn · Markdown: https://rewindex.com/company/mailjet/incidents/6cp6q10lvckn.md · JSON: https://rewindex.com/api/v1/companies/mailjet/incidents/6cp6q10lvckn · Generated 2026-10-20T03:13:48.282Z