Well, there used to be big plans about X.400 to become the global
standard of messaging...
I used to work for a company that used PMDF to interconnect various X.400
systems that could not otherwise interoperate.
It made a fair bit of income for the company but I would prefer not to
end up working with X.400 again and I certainly won't be going near it
for a hobby!
Regards,
Peter Coghlan.