Re: Open Issue: Stored strings vs. queries.

On Thursday 13 February 2003 22:04, Paul Hoffman / IMC wrote:
<snip>
>  I cannot see how a header would be considered a query.
<snip>

OK, let's do a Gedankenexperiment:

I think we agree that the smtp slots have to be queries. (Else, a single 
intermediate MTA running oldVersion will break the transport of a 
newVersion-MUA-composed message to a newVersion-mailbox.

Consider the case of stored mail header field slots.

I want to send a message with an oldVersion MUA to a newVersion mailbox 
whose local-part contains a code point from the set
    U(oldVersion) \cap AO(newVersion)

My MUA will rfc2822-serialize the message, thereby checking that any 
to/cc/bcc address meets the requirements of oldVersion-stored 
addresses. The address for the newVersion mailbox will fail that step, 
since it contains a code point from oldVersion of the U set.

This way, only addresses meeting the requirements of stored addresses 
are permitted. This doesn't even change if the MUA keeps track of the 
user-entered address separately of the rfc2822 serialization (for later 
use in the smtp rcpt to command), since it is simply not permitted to 
put the address into the rfc2822 serialization.

The only option for the MUA would be to leave out any address that fails 
the stored requirements test, but not the query requirements test[1] 
from the rfc2822 serialization, but use the address in the RCPT TO 
command. Well, that's what spammers do...

Consider OTOH the case of query mail header field slots.

My MUA will detect that the mailbox meets the requirements of a query 
mailbox, and happily put the mailbox together with the others (if any) 
into both the rfc2822 serialization slots, as well as the SMTP slots. 
Sending succeeds.

Conclusion: If we want oldVersion MUAs to be able to send mails to 
newVersion mailboxes (ie. a mailbox whose address contains newly 
assigned code points), then rfc2822 slots need to be queries or - if we 
insist they are stored - MUAs be required to omit the newVersion 
mailbox from the message, but give it in smtp rcpt to.

Since the latter option isn't really an option (all mails from 
oldVersion MUA users would appear to be bcc'ed to me, with the BCC 
header stripped), the question boils down to:

Do we want oldVersion MUAs to be able to send messages to newVersion 
mailboxes?

My answer would be "Yes", since that's what I understand IDNA works hard 
to achieve for DNS (an oldVersion browser can still do a dns lookup of 
a newVersion IDN).

Marc

[1] If both fail, the address should be rejected.

-- 
Ich gegen meinen Bruder.
Ich und mein Bruder gegen unseren Cousin.
Ich, mein Bruder und unser Cousin gegen unsere Nachbarn.
Wir alle gegen den Fremden.
                                      -- Beduinen-Sprichwort

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