Cloud News

Microsoft Probes Exchange Online Mailbox Outage

Wade Tyler Millward

Microsoft first tweeted at 8:56 a.m. Pacific Wednesday about the issue. The company said it was resolved hours later.


Some users of Microsoft Exchange Online are unable to access mailboxes through any connection method, Microsoft reported Wednesday.

The Redmond, Wash.-based vendor first tweeted at 8:56 a.m. Pacific Wednesday about the issue, also called EX522020.

“Users are reporting receiving an error including ‘550 5.4.1 Recipient address rejected: Access denied’ and we are investigating further,” Microsoft tweeted.

[RELATED: Microsoft Hit With Teams, Microsoft 365 Outage Issues]

Microsoft Deals With Exchange Online Issue

CRN has reached out to Microsoft for comment.

At 10:23 a.m., Microsoft tweeted that, “Our telemetry indicates that the service has largely recovered. We’re continuing to investigate to determine the root cause and whether additional action is required.”

Microsoft said at 11:58 a.m. Pacfic Time that it’s “in the process of routing EOP traffic away from what appears to be the affected infrastructure as a potential mitigation strategy. More details can be found in the admin center under EX522020.”

By 12:59 p.m. ET, the problem was resolved. Microsoft said in a Twitter post.

“We’ve confirmed that rerouting EOP traffic to alternate infrastructure has resolved the user impact,” the company said. “More details can be found in the admin center under EX522020.”

The mass adoption of cloud computing tools means occasional but short-lived technical issues for IT professionals.

Microsoft-specific issues this year include an outage in January with Teams and Microsoft 365 and a separate outage that same month for multiple Microsoft 365 services including Teams and Outlook in North America.

Wade Tyler Millward

Wade Tyler Millward is an associate editor covering cloud computing and the channel partner programs of Microsoft, IBM, Red Hat, Oracle, Salesforce, Citrix and other cloud vendors. He can be reached at

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