Elevated inbound recipient rejected

Incident Report for mailgun

Resolved

On November 13th, Mailgun incorrectly rejected a subset of inbound emails with a 550 "recipient rejected" error. Senders received bounce notifications even though delivery should have succeeded.

Affected timeframes:
US region: 05:14 to 06:41 UTC and 14:55 to 15:48 UTC
EU region: 14:55 to 15:48 UTC

Based on our analysis, approximately 25% of US inbound traffic and 50% of EU inbound traffic had a chance to have been impacted during these windows. We're unable to provide exact counts due to gaps in our logging for rejected inbound mail, which we have since corrected.

Posted Nov 13, 2025 - 02:30 PST