> On 2 Feb 2026, at 19:05, John R. Levine <[email protected]> wrote: > >> I’ll add my support to (1). > > As do I. I would rather do this sooner than later because I also have run > into people who wrongly believe that it's important for them to spend time > and money adding ARC support to their code and I'd like to be able to tell > them, no, save your effort for DKIM2.
I added ARC support 6 years ago to certain largish PGP remailer and it has been sending large swaths of mail to the large mailbox providers, read: Google + Microsoft/Outlook, and as per some stats going around the Internet that is >70% of email worldwide. Noting that both Microsoft and Google both support ARC. As such, might be a good idea if it is decided to shutter ARC to have an exit plan for these setups... Thus a document to mark as historic and why it is marked as historic, thus what the short comings are and how to disable ARC support slowly, without it causing any delivery issues might be a good idea... As a side-note in the above codebase, when a message is received with a DKIM header, we replace the original "From: [email protected] <mailto:[email protected]>" with "From: jeroen=massar.ch@via.<domain>", then DKIM sign it with a key specific for that via domain. SRS effectively. I also set the Reply-To to the original From, unless it was already set. The original DKIM header remains, as such ARC primarily gives "provenance" of passing the message on, but is effectively signed with the domain's DKIM key and ARC, thus a receiver ignores the original DKIM key (which does not match the new From:) but still, with ARC, can verify that at our hop it was valid, as claimed by us. Disabling ARC thus removes the ability to verify that, but that requires trust in our hop anyway, that what we claim is correct. For obsoleting ARC. It would be good to have Google + Microsoft and others on board, have a time-line for when they turn it off. The headers included by senders become futile and ignored, thus another time-mark a few weeks after could be where software generating ARC headers stop doing that. Regards, Jeroen _______________________________________________ dmarc mailing list -- [email protected] To unsubscribe send an email to [email protected]
