Jeremy Harris wrote in <25aead67-8b9f-1db0-076d-12620a394...@wizmail.org>: |On 07/08/2023 05:22, Jesse Thompson wrote: |> For messages which are originally submitted as BCC and, depending \ |> on the circumstances, it's necessary for us to identify the recipient \ |> in the headers, what is/should be the standard header to use for \ |> this purpose? BCC? Forwarded-to? | |There is no such header. That's the whole point of a bcc; it's Blind. |If there was one it would have to be a separate message to the one \ |it is a copy of.
That was where Dave Crocker's per-RCPT-TO comes in. I did not know about draft-levine-dkim-conditional before, but what is wrong with extending DKIM as such, instead of having all those other things like DMARC etc. You could include some more tags in the DKIM signature, one that signals that another per-receiver DKIM signature MUST be present (in an "outer envelope", ie, in a line that passed aka already having been read when this one is seen), a special one that correlates a RCPT-TO to the checksum/xy of the full DKIM currently processed. A minimized variant. You could define a DKIM specific ML header that takes some fields and their bodies from the pre-resent message (maybe compressed, surely base64 encoded to make them joinable to a comma-separated list), and MUST include that in the DKIM signature. (So receivers can restore the original content of said headers, and compare it against the (still included) DKIM signature of an "inner envelope" (presuming that new headers in the outermost envelope continue to simply be prepended; of course some other headers are mixed or suffixed, mailing-list software often does this for the ML-specific headers). That is, enable restoration and DKIM checking of the original, pre-modified message. This re-enables proper SPF checking, at least during DKIM verification, and could thus restore mailing-list operation as was known for decades, unless i am mistaken. (In an all-DKIM world.) --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) _______________________________________________ Ietf-dkim mailing list Ietf-dkim@ietf.org https://www.ietf.org/mailman/listinfo/ietf-dkim
