Re: [idn] The report from the design team

[Keith Moore <moore@cs.utk.edu>]

> > to put the question in a more practical light: if someone sends
> > out mail with a return address that uses an IDN, is it acceptable
> > if the recipient cannot reply to that message unless his mail
> > reader and the chain of SMTPs between him and the original sender
> > support IDNs?
> 
> The end-user still has to upgrade the MUA to use ACE.  If he doesn't, then
> at least one of the SMTP servers will have to do the work (assuming they
> accept an unconverted IDN from the MUA in the first place) whenever the
> user clicks on the internationalized mailto: link.

you've changed test cases on me :)

the MUAs I use don't support mailto: links at all, so I don't care about
them as much as I care about reply functionality working.

(I generally find mailto: links pretty useless, since they force
me to use the web browser's mail reader, and they don't let me pick
and choose the addresses to which I want to send a single message.)

> We are talking about varying degrees of breakage. Anything that presents a
> process with a local-format IDN has the potential to break things if the
> systems aren't compliant with whatever solution is chosen, and this
> includes ACE. Breakage of some degree is absolutely unavoidable.

agreed.

> As for how a new DNS message format would address this problem, no mail
> server should accept MAIL FROM which includes a domain name that the MTA
> doesn't recognize as legitimate, so in all likelihood a new ESMTP
> extension would almost certainly be required in order to accomodate an IDN
> solution that uses longer labels/names or non-ascii characters in the SMTP
> envelope. This may be required even when ACE is used though. What then?

it would be possible to design an ACE that encoded a single IDN label
as multiple DNS labels.  we need some idea as to whether a single-label 
ACE that uses compression is "good enough" and I haven't seen that yet.

Keith