Microsoft Exchange Online Outage Disrupts Global Mailbox Access

Microsoft is addressing a significant outage affecting Exchange Online users worldwide, preventing access to mailboxes and calendars through various connection methods. The issue was first acknowledged by Microsoft at 06:42 AM UTC on March 16, 2026, with reports surfacing throughout the day. Users are experiencing difficulties with Outlook on the web, Outlook desktop, and Exchange ActiveSync. Although Microsoft indicated that telemetry shows some recovery, many customers continue to face access issues. Additionally, a separate outage is impacting the Microsoft 365 Copilot web sign-in page. Microsoft is making configuration changes to improve service stability. This outage follows a similar incident in January 2026 that intermittently blocked access via IMAP4 and another in November 2025 affecting the classic Outlook desktop client. The situation remains under investigation, and updates are being provided through the Microsoft 365 admin center.

Key Points: • Microsoft Exchange Online is experiencing a global outage affecting mailbox access. • The outage began on March 16, 2026, with multiple connection methods impacted. • Microsoft is implementing configuration changes to restore service stability.