It is unusually difficult for most people to obtain an S/MIME client cert and install it in Outlook (I have a 27 page writeup of how to do this).
Sixscape created a fully automated scheme (based on IRP) to allow these certs to be obtained and installed in Outlook (and other E-mail clients) in a matter of seconds, with no expertise in PKI needed.
SixMail is implemented as an “addin” for Outlook. Once installed, the next time you try to send a message, it will say “you don’t currently have an S/MIME cert, so I will get one for you”. It then uses IRP to obtain an S/MIME client cert from one of our CA partners (or your own in-house CA), and install it in Outlook for you. It also automatically builds a group address book in AD with every issued certificate, to simplify obtaining recipient certs. Finally, it can optionally securely escrow your key material in the event of key material loss, or so that your organization can recover encrypted files and messages in the event of key loss or employee leaving.
This makes it possible for any organization to deploy S/MIME (with just digital signatures, or also with encryption), with little or no expertise required by your users, and no risk of being unable to access messages (for compliance and business continuity).
SixMail requires our infrastructure to be deployed in your organization, and an addin for each participating user. It integrates with your organization AD. We will be glad to discuss deployment and cost issues with you.