This policy setting controls how Outlook functions when a root certificate is missing. If you enable this policy setting, ...

This policy setting controls how Outlook functions when a root certificate is missing. 

If you enable this policy setting, you can choose from three options that determine how Outlook functions when a CRL is missing. 

- Neither Error nor Warning. This option displays neither an error nor a warning, and enforces the default configuration in Outlook.
- Warning. This option ensures that Outlook displays a warning message when a CRL is missing. 
- Error. This option ensures that Outlook displays an error message when a CRL is missing. 

If you disable or do not configure this policy setting, users are not prompted with a warning or an error when a root certificate cannot be located.