Re: [ietf-822] Expires header field

[Keith Moore <[e-mail]>]

On 12/2/22 11:53, Dave Crocker wrote:

> The draft does not indicate in what way this specification is an 
> update or enhancement to the previous version.
>
> I suspect the change has more to do with use than semantics, and it is 
> explicitly no change in syntax.
>
> Consequently, it is probably less confusing to just limit the history 
> references to the history section.
>
> 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.

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

>> 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.

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

Keith