Then, what
But MIME is a message format. It is not a mail transport. It
does not make any transport related guarantees because that
is outside of its scope.
means?
Which part do you not understand?
What more do you want?
Guaranteed interoperability.
It would be nice that if my mail composer followed the MIME spec,
and if your mail reader followed the MIME spec, that would be
sufficient for us to interoperate.
But that is not the case, because the mail transport must
also work correctly, in that it delivers the messsage to
you without damaging it too much for you to read it.
So it appears that what you want cannot be acheived with MIME.
Keith