Subject: Re: [EAI] mailto:

From: Shawn Steele <[email-masked]>
Date: Sat, 8 Aug 2009 21:37:46 +0000

I'm happy with that logic... Esp if it means skipping downgrade and getting the rest done faster:)

Sent from my HTC FUZE™, a Windows Mobile® smartphone from AT&T

-----Original Message-----
From: John C Klensin <[email-masked]>
Sent: Wednesday, August 05, 2009 1:34 AM
To: Shawn Steele <[email-masked]>; [email-masked] <[email-masked]>
Subject: Re: [EAI] mailto:

--On Wednesday, 05 August, 2009 07:23 +0000 Shawn Steele
<[email-masked]> wrote:

>...

> Specifically I meant that I don't think the <> downgrade
> syntax is helpful in mailto: since nobody's enabled by it and
> anyone that was updated to understand the <> in mailto:
> wouldn't need the downgrade for mailto:.

I think this (your observation and that from Charles) is a
corollary of some growing concern about forward-pointing
addresses and downgrade... see Ernie's recent note.  I also
observe that, for mailto, there is an already-deployed
alternative for two-address mailto.  We see it all the time in
messages and text, usually as

    mailto:[email-masked]  or mailto:[email-masked]

or even

    mailto:[email-masked]  (preferred) or mailto:[email-masked]

if one of them contains non-ASCII elements, e.g.,

    mailto:[email-masked]  or
      mailto:[email-masked]

nothing is lost and some small bits are gained.

That also suggests a way to do forward-pointing robustness on an
individual message basis.  Again, it is an extension of
something common.   Suppose I have two addresses for you,
[email-masked] and a hotmail address,
[email-masked] (I am obviously just making up the
second).  I know you are taking some vacation, I want to be sure
to reach you, but I don't know which one you are most likely to
read and don't even know if you are still maintaining the
hypothetical hotmail account.  To maximize the odds of something
getting through, I send the message to one address, copying the
other.  If one message gets through and the other bounces, no
problem.  The worst case is that you get two copies and I
apologize later.  On that model, the header syntax for
forward-pointing alternate addresses (without all of the
complications of downgrading) is

   To; [email-masked]
   cc: [email-masked]

The EAI alternative is obvious.

What disappears is the complexity of downgrading those
addresses, the security and other concerns about linked
alternative addresses (the linkage here is entirely in the mind
of the sender) and the need to change infrastructure -- not only
the <... <...>> form, but address book formats, message store
formats, etc.-- to accommodate the formal alternate addresses.

> In downgraded headers <> could be interesting, except as
> mentioned earlier that there are few scenarios where
> downgraded headers are actually round-tripped an made use of.

Yep.

    john