Mailjet incident
Microsoft Incident Resulting in Delivery Issues to M365
Resolved after 31 minutes, on September 4, 2026.
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. No other email providers are currently affected.
Update timeline
- monitoring Sep 04, 2026, 12:23 PM 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. No other email providers are currently affected.
- resolved Sep 04, 2026, 12:55 PM UTC
This incident has been resolved.
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