Microsoft Exchange Online Mailbox Access Outage Affects Users Globally

Home Cyber Security News Microsoft Exchange Online Mailbox Access Outage Affects Users Globally Microsoft is currently investigating a service disruption affecting Exchange Online users who are experiencing difficulties accessing their mailboxes through one or more connection methods. The issue, tracked under Microsoft 365’s service health dashboard, has prompted multiple status updates throughout Monday, March 16, 2026. Reports began surfacing earlier on Monday, with Microsoft issuing its first formal acknowledgment at 4:26 PM IST. Subsequent updates followed at 4:53 PM and 7:49 PM IST, indicating that the company’s engineering teams are actively working to identify the root cause and restore full service functionality. The incident affects Exchange Online, Microsoft’s cloud-hosted email and calendaring platform, which serves millions of enterprise and business customers worldwide. WE'RE INVESTIGATING REPORTS OF SOME USERS EXPERIENCING ISSUES WHEN ACCESSING THEIR EXCHANGE ONLINE MAILBOX VIA ONE OR MORE CONNECTION METHODS. MORE INFORMATION MAY BE FOUND IN THE MICROSOFT 365 ADMIN CENTER UNDER EX1253275. — Microsoft 365 Status (@MSFT365Status) March 16, 2026 Affected users may find themselves unable to connect to their mailboxes via clients such as Microsoft Outlook (desktop and mobile), Outlook on the Web (OWA), and potentially third-party email clients relying on protocols like MAPI, IMAP, or EWS. The scope of impact, as described in the advisory, spans one or more connection methods, suggesting that not all access pathways are uniformly affected. The disruption appears to impact a subset of Exchange Online users, though Microsoft has not yet publicly disclosed the exact number of affected tenants or geographic regions involved. Organizations that rely heavily on Exchange Online for day-to-day communications, including email workflows, calendar scheduling, and shared mailbox access, may experience intermittent or persistent connectivity failures during this window. Microsoft’s Response Microsoft’s 365 service health portal has been updated multiple times, with the engineering team working toward resolution. Users and IT administrators are advised to monitor the Microsoft 365 admin center’s Service Health section for real-time updates. The company has committed to providing further updates as the investigation progresses. As a workaround, administrators may consider directing users to alternative access methods that remain unaffected, such as switching from a desktop client to Outlook on the Web, or vice versa, depending on which connection method is experiencing disruption in their environment. Recommendations for IT Administrators Check the Microsoft 365 admin center under Health > Service Health for the latest incident updates Identify which specific connection methods are impacted in your tenant Communicate service status clearly to end users to reduce helpdesk ticket volume Consider temporary workarounds using unaffected access methods Document impact scope internally for SLA or compliance records Microsoft has not yet attributed the disruption to any specific infrastructure change, deployment update, or configuration issue. Further technical details are expected in subsequent updates as the investigation continues. Follow us on Google News, LinkedIn, and X for daily cybersecurity updates. Contact us to feature your stories. RELATED ARTICLESMORE FROM AUTHOR Cyber Security News Betterleaks – A New Open-Source Tool to Scan Directories, Files, and Git Repositories Cyber Security News Konni APT Hijacks KakaoTalk Accounts to Spread Malware in Multi-Stage Spear-Phishing Campaign Android Android 17 Advanced Protection Mode to Block Malicious Service Usage Top 10 Essential E-Signature Solutions for Cybersecurity in 2026 January 31, 2026 Top 10 Best Data Removal Services In 2026 January 29, 2026 Best VPN Services of 2026: Fast, Secure & Affordable January 26, 2026 Top 10 Best Data Security Companies in 2026 January 23, 2026 Top 15 Best Ethical Hacking Tools – 2026 January 15, 2026