Microsoft plans to block access to Exchange Online for any mobile devices using outdated email software. Specifically, devices running Exchange ActiveSync (EAS) versions below 16.1 will be cut off after March 1, 2026. EAS is the protocol that syncs email, calendar, contacts, and tasks on mobile devices. This change will impact only those using native email apps connected to Exchange Online, while users of Outlook Mobile will remain unaffected since it doesn’t depend on EAS. Apple’s iOS Mail app is already compliant, as it has supported ActiveSync 16.1 since iOS 10. However, other major email apps, like those from Google and Samsung, are in the process of updating to the necessary version. To help organizations prepare, Microsoft provided a PowerShell command for IT administrators to identify devices still using older EAS versions. The company emphasizes that keeping devices updated will minimize service disruptions. This shift follows discussions with various vendors to ensure a smooth transition for users.