Specifies if CRL check is mandatory.
This property affects result of certificate validation when CRL retrieval fails. If MandatoryCRLCheck = true and the CRL can not be retrieved, the certificate is reported to be invalid. If MandatoryCRLCheck = false and the CRL can not be retrieved, certificate validation continues. In both cases, when the CRL can not be retrieved, vrCRLNotVerified flag is included to Reason status of certificate. The default value is True.