Microsoft to end Client Access Rules support in Exchange Online by 2023

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Microsoft has announced it will retire Client Access Rules (CARs) in its Exchange Online platform by September 2023.

CARs allow Microsoft 365 administrators to filter client access to Exchange Online by combining conditions, exceptions, actions, and priorities.


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"Today, we are announcing the retirement of CARs in Exchange Online, to be fully deprecated by September 2023," the Exchange Team said.

"We will send Message Center posts to tenants using client access rules to start the planning process to migrate their rules."

Per reports, beginning October 2022, the company will disable client access rules for unused tenants. By September 2023, Microsoft will assist all remaining tenants in migrating from CARs to newer access control features such as continuous access evaluation (CAE)

"Now with new features, like Continuous Access Evaluation (CAE) that allows Azure Active Directory applications to subscribe to critical events, that can then be evaluated and enforced in near real time; you can have better control while also adding resiliency to your organization," the Exchange Team added.

As part of its effort to bolster Exchange Online’s safeguards, Microsoft has also warned customers that basic authentication will be disabled by October 1, for randomly selected tenants.