Google, Yahoo and Microsoft, the big providers all use ARC, and have used it for years. But Wikipedia doesn't have much nice to say about it.

--> allows a receiving service to validate an email when the email's SPF and DKIM records are rendered invalid by an intermediate server's processing. ARC is defined in RFC 8617, published in July 2019, as "Experimental".

It sounds like a Microsoft/Google/corporate standard, not IETF. I do seem to have trouble communicating with insurance companies' email systems in particular when I'm not using ARC on my email system, but outside the insurance industry -- and I'm making an educated guess that they are the main sticklers -- it doesn't seem to be a problem if SPF, DKIM, and DMARC are all working.


On February 9, 2022 6:16:19 AM AKST, Benny Pedersen <me@junc.eu> wrote:
On 2022-02-09 14:33, Aki Tuomi wrote:
We did that replacement for a while, but people complained. We have
ARC signing there, unfortunately it only works if you trust it.

ARC-Authentication-Results: i=1; talvi.dovecot.org;
  dkim=pass header.d=open-xchange.com header.s=201705 header.b=kWkbHwXq;
  dmarc=pass (policy=reject) header.from=open-xchange.com;
  spf=pass (talvi.dovecot.org: domain of aki.tuomi@open-xchange.com 
designates
  87.191.57.183 as permitted sender) 
smtp.mailfrom=aki.tuomi@open-xchange.com

X-Spam-Status: No, score=-6.4 required=5.0 
tests=AWL,DKIM_INVALID,DKIM_SIGNED,
	HEADER_FROM_DIFFERENT_DOMAINS,KAM_DMARC_STATUS,LOCAL_HASHWL_ALL,
	MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_HOSTKARMA_W,
	RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_PASS,SPF_PASS,
	T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no

seems it breaks :/
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.