Re: [ietf-822] Expires header field

[Dave Crocker <[e-mail]>]

On 12/2/2022 10:46 AM, Keith Moore wrote:
>
> On 12/2/22 11:53, Dave Crocker wrote:
>
>> So for the Abstract, perhaps instead:
>>
>> The Expires message header field indicates when a message becomes 
>> valueless and can be deleted safely.  Recipients have the option to 
>> use this information, as guidance for further message disposition.
>>
> Or perhaps:
>
> The Expires message header field indicates a date-time after which the 
> author of the message believes that the message no longer has primary 
> relevance to its intended recipient(s). After that expiration 
> date-time has passed, an MUA may present the message in such a way as 
> to reflect the message's decreased relevance.   This field SHOULD NOT 
> be interpreted by intermediate systems (such as relaying MTAs or 
> delivery agents), and SHOULD NOT be used to trigger automatic deletion 
> of the message.
>
I like the first sentence, although I suggest primary -> intended.

The second sentence is seeking to give guidance about UI/UX design and 
therefore should be dropped.  We don't do that (well); by way of 
example, this guidance implies utility in displaying this information to 
the recipient, and there is no empirical evidence that's useful, and 
some that it isn't.

I like the third sentence.


> (though maybe it's better to avoid normative language in the abstract 
> and instead place it elsewhere in the document)
>
+1


>>> 1.  Introduction
>>>
>>>     The date and time of expiration can be used by the mailbox provider
>>>     or the MUA to indicate to the user that certain messages could be
>> which provider?  which MUA?  And what is the basis for having an 
>> originating system (mailbox provider) decide when a message expires?
>>
>> I suspect what is meant is:
>>
>> The data and time of expiration can be added by an author, to 
>> indicate when a message is considered no longer useful.
>>
> I interpreted "mailbox provider" to mean "recipient's mailbox 
> provider" rather than an originating system.   But since we 
> interpreted this differently, it appears that additional clarification 
> is needed.
>
the reader should not have to guess at the meaning; that I interpreted 
differently than you demonstrates why


> I'd prefer that this document align itself with established 
> terminology, when applicable, in preference to inventing new terminology.
>
+1

But I also don't know why operational platforms should be adding this, 
rather than the author (or maybe the recipient).


d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net
mast:@[e-mail]