Intermittent Microsoft 365 Service Disruption

Microsoft has reported an issue affecting multiple Microsoft 365 services. According to Microsoft, a portion of their underlying service infrastructure was not processing traffic as expected, which impacted load balancing and overall service availability. Microsoft is actively investigating and addressing the issue under incident ID MO1221364, as published in the Microsoft 365 Service Health and Admin Center.

Services Potentially Impacted
Microsoft has confirmed that the following services may have experienced intermittent disruption:

• Exchange Online / Outlook
• Microsoft Teams
• Microsoft Defender
• Microsoft Purview
• Microsoft 365 Admin Center and security portals

Microsoft has classified this as service degradation, not a full global outage.

User‑Visible Impact
As communicated by Microsoft, affected users may have experienced:

• Delays or failures when sending or receiving email in Exchange Online
• Temporary SMTP errors, including 451 4.3.2 messages
• Intermittent access issues to Microsoft 365 portals, including Defender and Purview
• Authentication and connectivity interruptions across Microsoft 365 workloads including Outlook, Teams etc.
  
  

Scope of Impact
Microsoft indicated that the issue primarily affected users served through impacted infrastructure in North America. The impact was intermittent, meaning not all users or tenants were affected at the same time.

Current Status
Microsoft has confirmed that:

• The affected infrastructure has been identified
• Active remediation efforts are underway
• Service traffic is being rebalanced to restore full availability
• Customers should continue to monitor incident MO1221364 in the Microsoft 365 Admin Center for official updates

Please reach out to our team of experts at service@helient.com if you need assistance assessing impact or planning remediation.