This ("if the prot-article had both a Message-ID header field and a Date header field") is the place that bothers me most, since it will mean that singly injected articles produced by "modern" UAs that generate their own message-IDs will never get an Injection-Date header field.- <t>The injecting agent MUST then add an Injection-Date header - field containing the current date and time.</t> + <t>If the proto-article already had an Injection-Date header + field, it MUST NOT be modified or replaced. If the + proto-article had both a Message-ID header field and a Date + header field, an Injection-Date header field MUST NOT be + added, since the proto-article may have been multiply injected + by a posting agent that predates this standard. Otherwise, + the injecting agent MUST add an Injection-Date header field + containing the current date and time.</t>
It seems to sacrifice a general goal (that messages should have Injection-Date) for a narrow benefit (that multiple copies of multiply injected articles that are injected over a large span of time won't be detected as duplicates by servers that check Injection-Date and ignore Date).
I'm not sure that's the right tradeoff.
Harald