Error message - Cannot import as there already is a certificate

When importing a certificate in the Exchange Management Shell, the following message may appear:

Error Message - Cannot import as there already is a certificate with a thumbprint of ...

This error message appears when importing a certificate in Exchange where the certificate is already known in IIS.

You will therefore only have to activate the certificate using the following command:

Enable-ExchangeCertificate -Thumbprint "number series thumbprint" -Services "POP, IMAP, SMTP, IIS"

The Thumbprint can be found by double-clicking on the certificate and scrolling down on the Details tab. See also:

SSLCheck

Our SSLCheck will examine your website's root and intermediate certificates for correctness and report any potential issues