On Sat, 17 Dec 2022, S Moonesamy wrote:
I read draft-billon-expires-08 quickly. Section 2 states that: "Message creators MUST NOT include more than one Expires header field in the message they send." The statement, if I am not mistaken, ought to be read as an absolute prohibition. The next statement recommends (SHOULD) that the Expires header field ought to be ignored if there is more than one Expires header field. What are the valid reasons for ignoring an absolute prohibition?
They're advice to different parties. The MOST NOT is for people creating messages, the SHOULD is to people reading them.
The header field is currently in use in controlled environments, e.g. the military. I am not entirely convinced that it would be great to use the "lose its validity" feature for email over the Internet, excluding the notifications from social networks, as it moves the bar from "message was not received" to "Inbox message was not displayed".
It's also in use in X.400 gateways if any of those still exist. In real mail systems there are already plenty of reasons a message would be received and not displayed, most likely because it was stored in a spam folder, so I don't see what new problem we have here.
Regards, John Levine, johnl@xxxxxxxxx, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. https://jl.ly -- last-call mailing list last-call@xxxxxxxx https://www.ietf.org/mailman/listinfo/last-call
