Users of Office 365, hosted by Microsoft, may receive repeated credential prompts within the Outlook client. Per Microsoft, users that have access to other protocols such as Outlook on the web or mobile devices can access their email without issue.

Microsoft has posted the following health advisory regarding these issues:

  • Current status: Microsoft is continuing deployment of the fix and expect it reach all of the affected environments within the next 72 hours.
  • Scope of impact: This issue affects a subset of customers and users who are connecting to the service using Basic Authentication and utilize service-based search or a Focused inbox.
  • Start time: Tuesday, May 5, 2020, 12:00 AM (4:00 AM UTC) Preliminary root cause: A recent update to the Exchange Online service contains a code issue that is causing repeated credential prompts for basic authentication users

These issues are solely on the Microsoft systems. If you are experiencing issues, we will be happy to record and report to Microsoft on your behalf.