Microsoft confirmed a widespread Microsoft 365 outage affecting Outlook, Exchange Online, and several admin services across North America due to infrastructure issues. Users may see a “451 4.3.2 temporary server issue” error, and Microsoft has not yet given an estimated recovery time.
A widespread Microsoft outage disrupted multiple Microsoft 365 services across the United States on Tuesday afternoon, leaving many users unable to access key platforms including Outlook, Exchange Online, and administrative portals. Microsoft said it has identified the issue but has not yet provided an estimated time for full recovery.
Microsoft first acknowledged the problem in a post on X, stating: “We’re investigating a potential issue impacting multiple Microsoft 365 services, including Outlook, Microsoft Defender and Microsoft Purview. Further information can be found in the admin center under MO1221364.”
What’s Causing the Microsoft 365 Outage?
According to Microsoft 365 Status, the company has identified a failure within its North America infrastructure. “We’ve identified a portion of service infrastructure in North America that is not processing traffic as expected,” Microsoft said, adding that teams are “working to restore the infrastructure to a healthy state to achieve recovery.”
The root cause was described as a portion of dependent service infrastructure in the North America region failing to process traffic normally.
Services Impacted and Error Message Seen
Users affected by the outage may encounter a “451 4.3.2 temporary server issue” error when attempting to send or receive email through Outlook.
Microsoft said the following functions may be impacted, though the list is not exhaustive:
- Sending and receiving email through Exchange Online, including notification emails from Microsoft Viva Engage
- Delays or failures when collecting message traces
- Search delays or failures within SharePoint Online and Microsoft OneDrive
- Difficulty accessing service portals, including Microsoft Purview, Microsoft Defender XDR, and the Microsoft 365 admin center
Current Status and Scope of Impact
Microsoft said it is continuing to assess what actions are required to restore services and rebalance traffic:
“We’re continuing to review what actions are required to restore the affected infrastructure to a healthy state and rebalance the service traffic to achieve recovery.”
The company noted that any users served through the affected section of infrastructure in North America may be intermittently impacted.