Microsoft is investigating yet another worldwide outage, this time affecting Exchange Online, its cloud-based email service. The problems reportedly started around 1 PM UTC (7 AM ET).
The Microsoft 365 Status Twitter feed states: “We are investigating an issue in which users may be unable to access their Exchange Online mailboxes through any connection method. Additional details can be found in the Service Health Dashboard under EX522020.”
Thread continues, “user” 550 5.4.1 Recipient Address Rejected: Access Denied Reporting receiving an error including “We are investigating further.”
bleeping computer reports that Microsoft issued a service health alert at 5:22 PM UTC saying that it has identified a potential Directory Based Edge Blocking (DBEB) issue, and is investigating further. DBEB allows administrators to reject messages sent to invalid recipients in Exchange Online.
The company said that “the impact is specific to users that are served through the affected infrastructure in North America, Europe and the United Kingdom.”
As of approximately 3 p.m. ET, Microsoft tweeted that it is now diverting traffic from affected infrastructure as a possible mitigation strategy.
We’ll update this story when more information becomes available.