The present invention uses Server-based Certificate Validation Protocol (SCVP) to validate the public key digital signature certificate of an email signer (or the public key encryption certificate of an email recipient) by using a modified SCVP server such that a trustworthiness indicator based on certificate policies is included in an SCVP server response that maps the certificate policies asserted in the public key certificate of the email signer (or email recipient(s)) to graphically represent the degree of trust that can be attributed to the identities bound to public key certificates containing one or more certificate policies. The graphical representation of a trust level may appear directly in an email client and is based on the level of trust attributable to the binding between the public key distributed via a public key certificate (for signing or encryption) and the identity/attributes of the “subject” or “entity” contained in that certificate.