Re: Intent to revive "expires" header from draft-ietf-mailext-new-fields-15

On Wed, 2008-07-23 at 08:16 -0400, Keith Moore wrote:
> Frank Ellermann wrote:
> > Paul Smith wrote:
> > 
> >> All I can figure out so far is that the expiry of a
> >> message implies it's possibly not quite as important,
> >> urgent or valid to the sender/recipient/some-other-
> >> person as it would have been before it expired.
> >  
> >> I'm not sure that's a tight enough definition :)
> > 
> > From a sender's POV "expired" could mean "if you read
> > this mail later whatever I wanted is not more relevant".
> 
> How about this: "The sender believes this message will be irrelevant 
> after the indicated date/time."
> 
> "This field is primarily intended for use between senders and recipients 
> and their agents, rather than by message transport.    It is suggested 
> that the default behavior of an MUA with respect to the expires header 
> field should be to display such a message in a distinguished way.  For 
> example, the message could be displayed with gray text rather than 
> black, or in a different font than normal, or (in summaries) with an 
> image of an hourglass with the sand at the bottom."
> 
> "It is also suggested that MUAs allow setting of an expiration date as 
> an option when composing messages"
> 
> "MUAs, Message Stores, and MTAs, MUST NOT delete a message on the basis 
> of an Expired header field unless given explicit instructions to do so 
> by the recipient."
> 
> "Mail Filters MUST NOT consider an expired header field as criteria to 
> be considered for deleting the message unless given explicit 
> instructions to do so by the recipient"
> 
> behavior for mail-to-NetNews gateways should also be specified.

Beautiful! in particular the semantics, "The sender believes...
irrelevant..." - that's concise, and exactly the meaning we're
looking for, I think.

Cheers,
Michael