The flip side is that any such implementation which encountered an 8
bit character would not be able to do anything anyway so this is not a
big lose, so long as 7 bit filenames would be subject to a new
restriction that prevent the use of quoted-printable.
pardon my sloppy writing. Let me try again.
If we used encoded words, 7 bit ASCII filenames would need to be
#Prohibited# from being encoded in an encoded-word. Because the 7 bit
filenames which are currently usable by current RFC1341 MIME complient
mail agents would not be subject to a encoded word, older
implementations would not "break" when receiving mail from a newer
implementation. Older implementations would simply not be able to deal
with "enhanced" filenames when they begin to see regular use.
Do note that the use of 8 bit filenames in mail servers and in FTP
servers are not currently supported. The use of 8 and 16 bit
characters is only an issue when using local or distributed filesystem