Summary
Certificate-based signing of PowerShell serialization payloads was introduced in the January 2023 Exchange Server Security Update. By default, the feature was released as disabled (opt-in) and had to be enabled by the Exchange Server administrator.
By installing the November 2023 (or later version) Exchange Server Security Update, the feature is enabled by default (opt-out) on a per-server basis, and has to be disabled if you don't want to use it.
Caution: Disabling certificate signing of PowerShell serialization payloads makes your server vulnerable to known Exchange Server vulnerabilities and weakens protection against unknown threats. We recommend that you leave this feature enabled.
For more information, see Configure certificate signing of PowerShell serialization payloads in Exchange Server.
