The validation of DigiCert S/MIME certificates is as strong as that for TLS/SSL certificates. DigiCert S/MIME certificates are generally issued via a digital ID for individuals and departments in a company.
The DigiCert S/MIME Class1 is subject to domain or email validation (DV). Confirmation of the certificate is carried out via the email address. The certificate does not include any other information for the recipient.
The S/MIME Premium and Digital Signatur Plus certificates are organization validated (OV). This entails authentication of the organization by verifying ownership via a call to the human resources department using a telephone number from a public listing as well as information from the commercial registry. The information about the company is included in the certificate and can be viewed by recipients.
In this way, sensitive data is effectively protected, manipulation is prevented and the sender's integrity is clearly established.