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

2008-07-29 10:42:12

On Tue, 2008-07-29, Michael Welzl wrote:

On Tue, 2008-07-29 at 00:40 -0400, Hector Santos wrote:
Frank Ellermann wrote:
Russ Allbery wrote:

usepro doesn't define header fields.  Header fields are
defined in usefor.  From draft-ietf-usefor-usefor-11.txt:

ACK.  Keith kind of insisted that there must be some issue
with news in the proposal for mail, and I double-checked
that this isn't the case.

IMV, the only difference is that news processing does not have to 
concern itself with USER options.

    For news, Expires has been processed as a removal concept.
    i.e, the news article is no longer available and/or truncated.

Keith desires user permission.  Difficult to apply in news groups.

but we're not redefinining Expires for newsgroups. There is
some similarity between these two things here, but it's
not exactly the same.

I believe that conflating netnews and email is very misleading here.

The difference is in the concept of "ownership."

In netnews the tradition is that the originator of a message "owns" it.
Thus the author is empowered to cancel a message that he or she has posted
and to suggest the lifetime of that message by using the "Expires:" field.

However the tradition in email is that once the message is sent it is
"owned" by the recipient. Thus we have requirements that each hop make best
efforts to deliver the message and not to frivolously drop it if delivery
ia delayed. We also have not smiled on various attempts to construct a
mechanism to cancel an email once sent but perhaps not yet read.

As far as Expires: is concerned, a conflict may seem to arise in the area
of retention policy when a recipient is using an employer's systems and
equipment to receive the message, but an analysis of the "ownerships"
involved will usually resolve it. But notice that the Expires: does not
come from either of the "owners" of the message.

Bill McQuillan <McQuilWP(_at_)pobox(_dot_)com>

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