Microsoft released Exchange 2019 CU13 in May 2023. Anyone using Exchange 2019 is recommended to deploy this latest cumulative update. This is also known as the Exchange 2023 H1 update.

The major feature for this release is support for Modern Authentication, with the intention to prevent the use of basic authentication. Modern Authentication will allow for MFA to be supported for accessing Outlook mailboxes over an external web browser, for example. This feature will be available on a per user basis to allow for testing.

Microsoft have also added support for backing up more of the configuration files during setup, allowing for this info to be retrieved if desired after the setup process.

To apply this update the latest versions of either Exchange 2016 (CU23) or Exchange 2019 (CU11) need to within your Exchange Org.

If you are planning to migrate from Exchange 2016 or Exchange 2019, to O365 then this update should be applied. Make sure you check AD schema requirements also, and ensure your AD Forest can support them.