ietf-822
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Re: IDN (was Did anyone tell Microsoft yet?)

2002-04-30 06:41:19

also, even if transports are "munge free", that doesn't mean that they
can parse utf-8 headers correctly.  and various kinds of transports
do parse headers.

OK, so which headers do transports need to parse?

In practice, things that handle mail (like mailing list software,
gateways, virus filters,  spam filters, etc. - certainly not just 
MTAs) parse most of the structured fields for one reason or another.  
Several of them also try to rewrite such fields or to correct 
apparent errors in such fields - for instance, by taking strings 
of illegal characters and quoting them according to RFC 2047
(regardless of where those characters appear in the header).
I've also seen illegal characters replaced by \XXX where XXX is
the octal representation of the codepoint.

It's silly to assume that hundreds of implementations of mail 
software, some of them more than 20 years old, are going to do 
reasonable things with significant amounts of input that is 
clearly illegal according to the specifications for which those
programs were written.  

Keith