Critical incident

Dartmouth College: Dartmouth emails to external recipients are failing

Affected: M365 email

Current status of Dartmouth College: Operational — live Dartmouth College status

Timeline

1. Sep 17, 2026, 00:26 UTC
   identified
   We have identified an issue where Dartmouth users sending emails to external recipients are failing. The emails bounce back with an error message. We are opening a ticket with Microsoft and continuing to investigate a resolution.
2. Sep 17, 2026, 02:03 UTC
   identified
   We have temporarily disabled Listserv capabilities to reduce the number of external emails that are being sent as we work through this issue.
3. Sep 17, 2026, 03:15 UTC
   resolved
   The issue has been resolve by Microsoft and we are currently moving to a monitoring mode to ensure there are no further issues.

Updates as published by Dartmouth College (original).