The MIME type for application/pkcs7-mime was registered in RFC2311 (March of
1998). All applications should at the very least be prepared to parse this
as equivalent to application/x-pkcs7-mime, if not emitting it as well.
Our products don't emit it, but we can parse both. I'm fixing it. Everyone
else, please do the same (emit application/pkcs7-mime and recognize both
versions). Part of the reason that I emitted the x- variant was because
other applications couldn't read the non-x- variant. I suspect that this
should stop on the anniversary of the registration of the MIME type.
Applications may also wish to put in a way to force the outgoing MIME type
to be the x- variant as a configuration option, just in case.
Flames / comments welcome.
Blake