Re: Another issue: quoting

begin  quotation by Roy Badami on 2003/2/14 0:49 +0000:
> I would therefore propose that we consider defining a grammar for
> internationalized local parts based on the 2822 grammar.  As a result,
> any localpart that contains a non-ASCII character MUST NOT contain any
> of the following:
>
>    quoting (ie backlash or double-quote)
>    whitespace
>    any ascii character that is not permited unquoted.
>
> Opinions?

While we should ban all use of obsolete 2822 grammer with non-ASCII chars, 
we should support the full richness of the legal to generate grammer for 
2822 with non-ASCII chars for consistancy.  The extra work is not that hard:

1. remove "@domain" from addr-spec

2. if LHS starts with double-quote, strip surrounding double-quotes and 
internal use of "\" as the quote for a quoted-pair.

3. apply IDN transformation.

I would argue that step 2 is sufficiently simple that it's not worth 
banning potentially useful address syntaxes (like "Common Name"@domain). 
The reverse transformation for step 2 is a bit more complex:

2-reverse:  if output of IDN decode contains any of: 2822-specials, 
US-ASCII whitespace, leading or trailing "." or embedded "..", then wrap 
with double quotes and apply quoted-chars where necessary.

This is still simple compared to all the IDN gunk.

                - Chris