Microsoft Exchange Online Outage Causes Email Delays Across US, APAC, Europe
Published
Key Takeaways
- Global Mail Disruption: Microsoft Exchange Online experienced widespread email delivery failures across North America, Asia-Pacific, and Europe.
- Incident Tracking: Microsoft acknowledged the outage, tracked as EX1331830, at 10:33 EDT on June 2, 2026.
- Recovery Under Investigation: Engineers are analyzing the mail queue backlog to isolate the root cause and potential points of failure.
Microsoft is actively working to resolve a widespread service disruption affecting the email flow pipeline for Exchange Online customers across North America, Asia-Pacific (APAC), and Europe. The company first acknowledged the incident, tracked as EX1331830, at 10:33 EDT.
After initially focusing on North America and Germany, Microsoft expanded the scope to include APAC and Europe, noting it is analyzing the mail queue backlog for all affected regions to isolate potential points of failure.
Microsoft Error Messages Reported by Affected Users
Affected users reported two distinct error types during the outage. Some encountered temporary SMTP deferral errors displaying the message: "The maximum number of concurrent connections per resource forest has exceeded a limit, closing transmission channel." Others saw "Connection was closed abruptly (SuspiciousRemoteServerError)" notifications.
Microsoft confirmed that users are experiencing significant delays in sending and receiving email messages, with some emails remaining undelivered for over an hour.
Microsoft classified the disruption as an incident, a designation typically reserved for critical service issues with noticeable user impact. The company stated its engineers are actively reviewing reports to identify the root cause.
Recent Microsoft Service Issues
The Exchange Online outage adds to a series of recent service disruptions across Microsoft's platform. Recently, Microsoft addressed an outage that prevented Teams and Office for the web users from opening files, as well as an incident that disrupted MFA setup and access to the My Sign-Ins platform.
In early April, a suspected Iran-nexus password spray attack targeted Microsoft 365 users in the UAE and Israel. Early this year, a major Microsoft 365 outage disrupted Exchange Online, SharePoint, and Teams access for enterprise customers in North America.
Related
Get expert insights on threats, breaches, scams, and security trends — delivered every Monday.
Most Popular
Get expert insights on threats, breaches, scams, and security trends — delivered every Monday.
Most Popular