On Sat, Mar 15, 2025, 1:50 p.m. Alessandro Vesely <ves...@tana.it> wrote:
> On Wed 12/Mar/2025 15:51:44 +0100 Allen Robinson wrote: > >> Definition of forwarding > > > > In the context of DKIM2, this is the act of accepting a message with > some > > 821.To address and resending it to some number of other 821.To > addresses, > > potentially after modifying the message. This definition covers most > MTAs, > > if I understand correctly. Needing to change the 821.From in this case > is > > certainly a large change for the ecosystem as a whole, but one that we > feel > > provides sufficient value to justify the cost. > > SMTP describes this as "Mailing Lists". > Mailing lists are one example. Other examples are autoforwarding support offered by mailbox providers, and aliasing services. > > I think an argument could be made that this definition doesn't apply to > all > > relays. Systems that don't need to change 821.From or 821.To and don't > modify > > the message being transferred would probably be able to operate without > > attaching their own signatures. > > > AFAIUI, only backup MXes can forward a message without changing 821.To. > There are also services referred to as "security gateways". These are external servers pointed to by a domain's MX records, and will generally relay to the domain's mailbox provider after doing filtering and/or rewriting of the inbound traffic. IIUC these will usually use the same 821.From and 821.To. > > If signing 821.To could somehow be made into a separate signature, the > "classic" alias forwarding would not break the other (part of the) > signature, > which would therefore be more compatible with DKIM1. Adding a tag to a DKIM1 signature that contains the 821.To wouldn't cause issues for existing verifiers. They wouldn't understand what to do with that information but that's ok. > > > Best > Ale > -- > > > > > _______________________________________________ > Ietf-dkim mailing list -- ietf-dkim@ietf.org > To unsubscribe send an email to ietf-dkim-le...@ietf.org >
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