Microsoft Exchange could not load the certificate with thumbprint of %1 from the personal store on the local computer. This certificate was configured for authentication with other Exchange servers. Mail flow to other Exchange servers could be affected by this error. If the certificate with this thumbprint still exists in the personal store, run Enable-ExchangeCertificate %1 -services SMTP to resolve the issue. If the certificate does not exist in the personal store, restore it from backup by using the Import-ExchangeCertificate cmdlet, or create a new certificate for the FQDN or the server enabled for SMTP by running the following command: New-ExchangeCertificate -DomainName serverfqdn -Services SMTP. Meanwhile, an ephemeral, self-signed certificate with thumbprint %2 is being used.