Re: changes between imaa-01 and -02

"J-F C. (Jefsey)  Morfin" <[email protected]> wrote:

> > Should IMAA support case-sensitive mail exchangers?  No.
>
> I thought we made clear that yes.  And that you made clear that
> punnycode had no problem with it.

There are at least three separate issues here.

1. Do josé@example.net and JOSÉ@example.net refer to the same mailbox?

[The non-ASCII characters just before the at-signs are e-with-acute and
E-with-acute.]

This was an open issue in imaa-00, but it was already closed in imaa-01.
There has been no change between imaa-01 and imaa-02 on this issue.  The
decision was that yes, they refer to the same mailbox, because that's
what most users expect, it is consistent with current practice, and is
consistent with the recommendation of current standards.

This issue is closed.

2. Will josé@example.net and JOSÉ@example.net be displayed that way, or
might they both be displayed the same way?

In other words, is case preserved?  This was an open issue in imaa-00,
but it was already closed in imaa-01.  There has been no change
between imaa-01 and imaa-02 on this issue.  The decision was that
they might both be displayed the same way, because preserving case
is too technically tricky to require of all implementations, and for
consistency with IDNA (where the existing recommendation that case be
preserved in ASCII names was relaxed for non-ASCII names).

In both IDNA and IMAA, it is possible to add optional support for case
preservation later, but it will not be in the initial RFC.  This issue
is closed.

3. Will it be possible to create a mailbox named josé@example.net or
JOSÉ@example.net if the mail exchanger for example.net is IMA-unaware
and case-sensitive?

This was an open issue in imaa-01, and has been closed in imaa-02.  The
decision is no, it will not be possible, because making it possible
would complicate the spec for almost zero gain, because all known mail
exchangers are case-insensitive anyway (which is what existing standards
recommend).

Of the three issues, this is the only one that changed between imaa-01
and imaa-02, but I think all of JFC's concerns pertain to the other two
issues, not this one.

Roy Badami <[email protected]> wrote:

> Mixed-case anotation, as I understand it, can't capture the
> distinction between ss, SS and es-zet.

Right, because ASCII letters are literal, not annotated.  An es-zet
becomes ss, which is regular ASCII.  It can appear as ss or SS or Ss or
sS, but those are all literal ASCII.

I suppose a special convention could be adopted that if mixed-case
annotation is enabled (which could be signaled by an ACE prefix of
xN--), then sS should be displayed as es-zet.  Of course that would make
it impossible to display sS itself.

There would still be other things that mixed-case annotation could not
handle, like titlecase (letter Dz versus letter dz or letter DZ).

> add a series of headers of the following form:
>
> IMA-Presentation-Form: <ASCII-email-address> <base64-encoded-UTF8-IMA>
>
> one for each IMA in the From/To/Cc headers.

That's both simpler and more expressive than mixed-case annotation,
which is attractive.  On the other hand, it would work only for mail
addresses in message headers, not for mail addresses and domain names in
other contexts.

AMC