Microsoft fixes Exchange sign-ins broken by Windows Server updates
Microsoft has resolved Outlook sign-in and mail delivery problems on Exchange Server systems that appeared after the October 2026 Windows Server security updates. The issue affected some on-premises Exchange servers, and Microsoft said in mid-October that the impact varied by server load. Exchange sign-ins and mail flow after October updates Microsoft said the sign-in and mail delivery failures came from a new default memory limit for Endpoint Mapper when it…