On Fri, Dec 2, 2022, at 13:35, Keith Moore wrote:
Expires could still be useful if the recipient's MUA displayed expiredmessages differently than normal messages, thereby alerting therecipient that the content is no longer timely, without actuallydeleting the message.
My use case (and the tooling I would build for myself if we don't make it a standard Fastmail feature) would be to flag particular senders as "auto-expire messages from this sender when their Expires header says to) - and I'd use for a bunch of transactional edge trigger "reminder" emails, which contain no content other than a "please go check over here".
For example: the "you have pending moderation messages" that Mailman sends every day. If the previous day's one expired at the time a new one would be sent out, I could have them auto-clear, and they would either have been superseded by a newer "you have things to action" email, or be no longer relevant.
Obviously, we all agree - and the draft agrees - that this MUST never be turned on by default. At least to the kind of MUST that you can apply on any system - business logic might automatically turn it on for some senders inside a business who know their own senders, and we can't force them to do otherwise with strong words in a draft - but generally I think the risks of defining this header with this behaviour are not as great as you suggest. Yes it could be abused but receipients with a legal requirement to not destroy emails will already have protections around archiving all incoming email and that's not going to change because there's a header there.
Bron.
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Bron Gondwana, CEO, Fastmail Pty Ltd
brong@xxxxxxxxxxxxxxxx
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