Starting March 1, 2026, Exchange Online will block devices using Exchange ActiveSync versions below 16.1 for improved security. Organizations must update mobile devices and apps to EAS 16.1 or higher. Outlook Mobile is unaffected. Admins can identify outdated devices using a provided PowerShell command.
Applies to: Exchange Online
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).