Microsoft is currently working to resolve ongoing access issues affecting Exchange Online. For the past three weeks, users of the Outlook mobile app and the Outlook for macOS client have been experiencing frequent connection failures.
The issue was first identified on March 11. Microsoft initially attributed the problem to a newly introduced virtual account and briefly marked it as "resolved" on April 1. However, subsequent reports indicated that the problem persisted, leading Microsoft to re-log the incident in the admin center under a new tracking ID (EX1268771).
Repair Efforts Continue
In its latest update, Microsoft stated: "We have received feedback from affected tenants confirming that the service impact described in EX1256020 persists. We are currently attempting to restart the Notification Broker service within the Exchange Online infrastructure to mitigate the impact on users while we continue to investigate the root cause."
Microsoft’s technical team noted that the issue manifests as intermittent access failures for users on the Outlook mobile app or the new Outlook for Mac desktop client. While the company has acknowledged the problem, it has not disclosed the specific geographic scope or the number of users affected. By classifying the event as an "incident," Microsoft typically signals that the disruption is having a significant impact on core services.
Exchange Online has faced multiple service interruptions in recent months. In January, the service experienced intermittent blocks on IMAP4 protocol email traffic. Last November, the classic Outlook desktop client suffered a similar large-scale access outage. Furthermore, earlier this month, Microsoft resolved a major disruption that prevented access to calendars and mailboxes across the web, desktop, and other connection protocols.
Although the team is taking additional measures to prevent a recurrence, Microsoft was still conducting a deep-dive investigation into the root cause of this outage as of Thursday evening.
