entra id certificate auth

Entra ID certificate auth is a method for authenticating users and devices using certificates through Microsoft Entra ID, replacing older direct authentication approaches. A recent Microsoft announcement indicates that Exchange Online will end direct Exchange ActiveSync certificate-based authentication by the end of 2026, requiring affected mobile mail clients to authenticate certificates through Entra ID instead of presenting them directly to Exchange. This change is part of Microsoft's broader effort to centralize authentication around Entra ID, impacting organizations that built mobile email around EAS client certificates. For most users, the transition will be seamless, but affected organizations need to plan for the migration.