I believe there are two things for S/MIME to be used as a standard. It
must be available on Unix mail programs (elm, pine, mailtool, whatever) or
even better as a command-line utility. It must be available as a public
domain package like PGP is.
And what is more important: it must come from free world and from USA.
People outside US will never use weak easily breakable crypto programs,
meaning that Netscape and Microsoft and PGP can just forget their