Microsoft says it is seeing improvements in traffic, but an outage affecting Outlook, OneDrive and several other services has lasted more than 18 hours.
The company first acknowledged outages for its email hosting platform Exchange Online at 5 pm BST on 31 August and identified an issue with an authentication component shortly after, which also affected other services.
By 11 pm, Microsoft said it was “testing and implementing various mitigations” and said mail traffic “queues are draining” by 6:24 am, but its service health page showed search and calendar issues persisting into the workday on 1 September.
Posting on X, Microsoft’s 365 team said investigations had found “that a misconfiguration issue may be preventing authentication components from deploying as expected to a portion of infrastructure.”
