We started getting errors in Outlook "The secutiry certificate has expired or is not yet valid." So, I went to Exchange Management Shell and created a new certificate using the following cmdlet: "Get-ExchangeCertificate -thumbprint 123456.... | New-ExchangeCertificate." I, then used the Enable cmdlet with the new thumbprint and typed in SMTP as the Service name. But, Outlook is still using the old certificate and is still giving the certificate error. What am I doing wrong? How do we get Exchange to use the new certificate?