Personally I am skeptical about the future of binary SMTP. Not even the
ietf-smtp group is currently contemplating a true binary extension. I
think it is good to have this placeholder in XXXX though, so that we
know how it will be marked if it ever happens, but beyond that I'm not
enough of a believer to want to go to great lengths to support it in
advance. Also, if they define a binary SMTP, they should put checksums
in at that level and it won't be NECESSARY at our level, because data
integrity will be assumed.
As for quoted-printable, I guess I'm just skeptical that a checksum is
necessary. If it isn't textual data, you probably won't use q-p. If it
is textual data, a checksum is highly problematic across, e.g.,
ascii-ebcdic gateways. So I just don't see it as being worth the effort.
Again, no showstoppers here for me either way. -- NB