MIME "8bit" have serious interoperabilitty problem, then.
Not at all. "C-T-E: 8bit" simply states "this message body contains
short lines of 0-255". I don't think there's any ambiguity in RFC-1521:
a conformant UA receiving such a message will handle it correctly.
That's the consensus I think exist but Keith disagrees.
I wasn't around at the time, but I believe the main intent of "8bit"
was to provide an easier upgrade-to-MIME path for those people who were
already using 8bit characters sets and "just-sending-8".
An ovbious reason that both "8bit" and "binary" exist is that RFC1426
supports "8bit" but not "binary".
As sendmail has been actively dropping the MSB, people have been using
7 bit character sets on the global Internet.
Masataka Ohta