Summary: Microsoft has announced a partial mitigation of a week-long Exchange Online outage that has caused significant email delivery issues for users worldwide. The incident, tracked as EX1027675, began on March 7 and involved a service update that inadvertently introduced a code issue affecting message transport services. A separate related incident (EX1030895) continues to cause intermittent delivery failures and issues with calendar invites.
Affected: Microsoft Exchange Online
Keypoints :
- Outage began on March 7, with critical service issues acknowledged on March 10.
- Users reported delivery failures, receiving “554 5.6.0 Corrupt message content” errors.
- Mitigation efforts included deploying a fix and offering ZIP files as a temporary workaround for attachments.
- A separate ongoing issue has been identified that intermittently triggers NDR failures for a small subset of messages.
- Microsoft is conducting targeted restarts and monitoring diagnostics to address ongoing problems.