Re: draft-klensin-emailaddr-i18n-00

Adam M. Costello scripsit:

> In any case, I think it would be good if receivers do not assume that
> text is already normalized; they should perform normalization whenever
> they want text to be normalized.  Then it will not be necessary for
> senders to perform normalization.  The implementation cost is the
> same whether the code is inside the senders or inside the receivers.

This is true for person-to-person email, but not for mailing list
postings, which are formally equivalent.  There, the efficiency is
much superior if senders MUST normalize and receivers SHOULD check
normalization, checking being much less costly than normalizing in
most cases.

> Forbidding unnormalized text on the wire doesn't do much except to make
> troubleshooting more difficult for humans, who cannot see the difference
> between normalized and unnormalized text.  It's not as if unnormalized
> text is ambiguous.  It makes sense to forbid ambiguous constructions
> like "user@foo@bar", but unnormalized text is not ambiguous--you
> can determine exactly what was intended by normalizing it yourself.

But if it is signed, you will destroy the digital signature.  What is
worse, a sender of unnormalized text may be able to spoof a receiver.
See the W3C's CharMod draft (http://www.w3.org/TR/charmod) for details.

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