none✓ Resolved

Email Delivery Failures to Microsoft 365 Domains

Mailgun•2026-08-17 20:18 UTC

Status

resolved

Duration

Updates

Coverage

0 articles

INCIDENT TIMELINE

✓ Resolved2026-08-17 20:18 UTC

This incident has been resolved.

resolved2026-08-17 20:18 UTC

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

📊 TECHNICAL DETAILS

Internal ID

e85cf859-2315-433c-a351-c8dc2f0ce28d

External ID

vwhk7lx3lvs3

🕐 Started

2026-08-17 20:18 UTC

🔄 Last Updated

2026-08-17 20:18 UTC

✓ Resolved

2026-08-17 20:18 UTC

NONE

Impact Level

Total Duration

Status Updates

Affected Components

Outbound Delivery

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