Mailgun outage, 17 August 2026

Email Delivery Failures to Microsoft 365 Domains

Started
Resolved
17 Aug 2026, 20:18 UTC
Impact
Not stated
Affected
Outbound Delivery

Last update from Mailgun

We have received confirmation that an external issue impacting email delivery to Microsoft 365 domains has been resolved. Impacted messages would have received an error stating "5.7.511 Access denied, banned sender" between Friday, August 14th and Monday, August 17th. Any failed messages will need to be resent. Information on retrying messages can be found in our Help Center here: https://help.mailgun.com/hc/en-us/articles/18596982041883-Resending-messages

17 Aug 2026, 20:18 UTC

Read the full incident on the official Mailgun status page

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Other Mailgun incidents

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  3. EU Messaging Outage

  4. Microsoft Incident Resulting in Delivery Issues to M365

  5. Event Log Delays in US Region

  6. EU Messaging Outage

  7. GCP Reporting Multi Service Outage in US-West1

  8. Click and Open Tracking Degraded (US Regions)

All recorded Mailgun incidents