The document entitled What is a PKI? from the "Treasury Board of Canada Secretaries" has a good explanation of PKI and concludes with:
"A Transparent and Seamless Operation
PKI's beauty is that it performs these encryption, decryption and
identity-verifying functions invisibly to Bob and Alice, while ensuring that
their transaction is nearly as private and secure as a face-to-face meeting."
We, at SAFe-mail, hope that our system really does create a PKI environment that is seamless and automated.