There is a technology from New Zealand called RPK
http://www.rpk.co.nz or http://crypto.swdev.co.nz that also is
available > in high strength and is currently being implemented as a
seamless add-in > for MAPI based e-mail packages (that covers >80% of
the market).
I looked at it - it appears to be compatible with neither S/MIME or PGP/MIME,
so it would appear to be a non-starter.
--
Lindsay Mathieson
Black Paw Communications
Using MailCat for Win32 Beta Vs 2.8 Preview 4, on February 4, 2000, in Win95
4.0
http://www.blackpaw.com/