Microsoft is resolving an Exchange Online incident that has incorrectly quarantined some customers’ mailboxes since July 19, causing email delivery failures and calendar access issues. The problem, tracked as EX1436407, was tied to an infrastructure change that triggered excessive memory use and has required additional remediation after a similar previous issue, EX1434354. #ExchangeOnline #Microsoft #EX1436407 #EX1434354
Keypoints
- Microsoft is fixing an Exchange Online issue that wrongly quarantined mailboxes.
- Affected users could not reliably send, receive, or access calendar data.
- The issue began on July 19 and remained unresolved in the latest update.
- Microsoft linked the incident to an infrastructure change and out-of-memory condition.
- Cleanup of excess indexing data is ongoing, with recovery progressing gradually.