exchange activesync

Exchange ActiveSync (EAS) is a Microsoft protocol that synchronizes email, calendar, and contacts between Exchange servers and mobile devices. Recent discussions on WindowsForum highlight Microsoft's plan to end direct EAS certificate-based authentication in Exchange Online by late 2026, requiring organizations to route certificate authentication through Microsoft Entra ID instead. This change primarily affects enterprises that built mobile email workflows around EAS client certificates, while most users will see no immediate impact. The shift reflects Microsoft's broader strategy to centralize identity management and phase out legacy Exchange authentication methods. Forum threads explore migration steps, compatibility concerns, and the timeline for this deprecation.