Microsoft Outlook outage: Here’s what we know so far

Microsoft has said systems are “gradually” recovering after an outlook Outlook.com outage that meant users might not be able to send, receive, or search for emails within the service due to a “recent change”. 

Microsoft acknowledged the service issues on Tuesday at 4:04 AM UTC and noted that it has impacted users in North America and other “additional regions”. The issue itself is due to a glitch impacting Microsoft’s infrastructure in North America. It has not clarified which additional regions are affected, but noted in an update that the Calendar application protocol interfaces used by Microsoft Teams and other services are also affected. 

However at 11.05GMT Microsoft tweeted:  “We’ve applied mitigation throughout the affected infrastructure, and we’re starting to see gradual recovery.”

Microsoft had detailed  the problem at 08:43 on its service health page. “Current status: Users in additional regions beyond North America may experience some residual impact due to the affected portions of infrastructure in North America. We’ve begun observing gradual improvement from this issue for users located in some of the additional affected regions. We’re continuing to perform targeted restart operations on the primarily affected infrastructure in North America in order to restore the availability of the service,” it said.

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Microsoft’s @MSFT365Status Twitter account reported that a “recent change” was contributing to the service disruption. It has not clarified what change it was referring to. 

“We’ve confirmed that a recent change is contributing to the cause of impact. We’re working on potential solutions to restore availability of the service. Refer to EX512238 or https://portal.office.com/servicestatus for more detailed information,” it noted. 

“Our targeted resources are progressing, and we’ve seen slight improvement in some environments. Alternatively, we’re exploring additional steps to expedite the resolution. More details are available via EX512238 in the admin center or http://portal.office.com/servicestatus,” it said in a later update. 

The current disruption to Outlook.com follows a global multi-hour outage at the end of January that impacted several Microsoft cloud services, including Microsoft Teams, Exchange Online, Outlook, SharePoint Online, OneDrive for Business, Microsoft Graph, Power BI, M365 Admin Portal, Microsoft Intune, Microsoft Defender for Cloud Apps, and Microsoft Defender for Identity. 

The company said in a preliminary post-incident review that “a change made to the Microsoft Wide Area Network (WAN) impacted connectivity between clients on the internet to Azure, connectivity across regions, as well as cross-premises connectivity via ExpressRoute.”

The outage happened after a command given to one of its routers in the WAN caused the router to send messages to all other rounders in the WAN to recalculate their IP tables. The particular command had not been vetted by engineers prior to deployment. 

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Microsoft plans to publish a final post-incident review report about the January outage by mid-February.