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Re: 7/8-bit conversion vs. bouncing

1991-07-01 19:33:19
Paul A Vixie <vixie(_at_)pa(_dot_)dec(_dot_)com> writes...

i would have been for it.  i don't want a new port number.  i don't want
local enclaves.  i want a straightforward, 1-to-1 mapping between 7 and
8 bits which is machine-detectable on the 7-bit end and which is mostly
readable if undetected all the way out to the recipient's display.
   I knew that taking your name in vain would get a rise out of you :-)

want all smtp clients which support 8-bit transport to be able to do the
8->7 conversion if they hand off to a non-EVFY-speaking server.
   No problem, although, as several people have pointed out (on and 
off-list) there may be some difficulties if you expect this conversion 
to be done in real time while the connection is open.
   But the important thing is that, if I may speak for the diehard "no 
conversions" community, we would read the above narrowly, agree with it, 
and then say something with which you might have a problem.  E.g.,
  (i) Every smtp client that supports 8-bit transport MUST be able to 
support 7-bit transport and SHOULD be able to do 8->7 translation.  Not 
being able to do so is not nonconforming, but is really stupid.
  (ii) relays are not smtp clients, and don't convert.  Relays should 
not accept mail in 8-bit transport form unless they are sure that they 
can make final delivery in that form (whatever "final delivery" means).

what is wrong with doing it this way?
  The only thing that is wrong with doing it this way is that we have 
moved beyond simple character mail and into very complicated stuff in 
which it may be very hard to guarantee "straightforward 1-to-1 
mappings".  Some of the things RFC-XXXX is designed to pass around are 
not "mostly readable" (or even a little readable) in any form--8-bit, 
7-bit, baudot,...--and none of the transformations we are contemplating 
make things any worse (or better).   Just in terms of opportunities for
information loss (and not trying to suggest that the tradeoff is
desirable), if an 8->7 converter can simply encapsulate the entire
message, the odds of ending up with a no-loss 1-1 mapping are much
higher than if that converter has to read, parse, and understand a
complex body part structure.