The disruption is pervasive. Users attempting to access Outlook.com are meeting persistent timeouts, while those relying on desktop clients—including Thunderbird—report an influx of errors.
The failure extends beyond web portals; according to documentation from Borns IT- und Windows-Blog, Exchange Online mailboxes are failing to initialize, leaving employees trapped on “Profile loading” screens and unable to send or receive mail.
On November 12, 2026, at 2:10 PM, the Microsoft 365 Status team stated via social media:
“We’re testing a configuration change to address a problem that’s causing servers to fail automated health checks and become unavailable. In parallel, we’ve initiated a restart of all affected servers and are monitoring health as they return to service.”
Microsoft has since initiated a restart of the affected server clusters. Administrative users can track the progress of these recovery efforts via incident codes EX1550543 and MO1550821 in the Microsoft 365 admin center status page.
Borns IT- und Windows-Blog has documented the breadth of the impact across the ecosystem, noting that the inconsistency in mailbox availability suggests that the synchronization of large-scale Exchange databases is still struggling to stabilize.
As of the time of reporting, crews are still recovering items. While server restarts continue, the company has yet to confirm full restoration for all regions. Users are advised to monitor the official status dashboard for updates, as the company continues to observe the health of systems attempting to return to an operational state.
