Murray S. Kucherawy wrote in <cal0qlwbs4i9xth2pp_mt-bvxndfsmbulb92r5k69dnyoxpm...@mail.gmail.com>: |On Sun, Apr 13, 2025 at 11:56 AM Richard Clayton <rich...@highwayman.com> |wrote: | |>>Bcc header field? Doesn’t that contradict the “blank” carbon copy? | |I think "B" means "Blind". | |> I suggest you read RFC5322 #3.6.3, which has quite a lot of text |> explaining the complexity of what a Bcc header field can look like. For |> length, I will not include that here. |> |> You can try arguing there is no value in signing the field because |> nothing ever displays it or acts upon its content ... I am not confident |> about that. |> | |I would argue that any value in signing the field is defeated by the fact |that it is supposed to get removed before it proceeds to delivery. Some |agents might remove it sooner than delivery. Removing a signed header |field has a negative impact at verification time.
Here i want to add two things. First of all i thought Richard Clayton also referred to the communication i had with John Levine on some lists, likely around January 2024, where he for some short time had convinced me to put empty Bcc: fields if only some Bcc: recipients did exist in the message. If i recall correctly the RFC does envision this as one vivid approach of dealing with the situation. In the meantime this is a compile-time option, default off (ie, we do not produce such fields). Second i also posted here somewhere about a problem i had encountered while maintaining that MUA (i sometimes work not talk, however hard that is to believe), and that is that certain MTAs do *not* remove -- in violation of RFC 5322 -- Bcc: header lines when invoked via command line interface and given a template message. My notices show that the exim and courier MTAs require a -t command line argument in order to remove the header field. (The MUA now provides a configuration option to actively remove Bcc:, and pass the recipients therein to the MTA via command line arguments instead.) --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 To unsubscribe send an email to ietf-dkim-le...@ietf.org
