18/01/2022 07:39:00 AM (GMT)
Microsoft Reference : EX315381
Issue Status: RESTORED
Issue Description: Users may be unable to access their Exchange online mailbox via any connection method.
Scope of impact: A small subset of users hosted out of the affected infrastructure may experience impact.
Final Update – 18/01/2022 07:39:00 AM : A portion of mailbox infrastructure facilitating access to Exchange Online mailboxes using basic authentication was operating below acceptable performance thresholds, inhibiting a subset of users from accessing their mailboxes via certain connection methods. Microsoft are continuing our review of diagnostic data in conjunction with service logs to isolate the cause of the processing inefficiency and develop long-term mitigation actions.