eas 16.1

Microsoft is enforcing EAS 16.1 as the minimum Exchange ActiveSync protocol version for Exchange Online connections, with a compliance deadline of March 1, 2026. Devices using older EAS versions will be blocked from signing in, which could cause user outages and increased helpdesk calls. IT departments must prepare by ensuring mobile clients and devices support EAS 16.1, often requiring updates to Outlook for iOS and Android or other mail apps. This change is part of Microsoft's broader push for modern authentication and security, including OAuth and Conditional Access. The tag covers the enforcement timeline, technical requirements, and operational impact of the EAS 16.1 mandate for enterprise IT administrators managing Exchange Online.