ARC

Back in October 2019, Microsoft included ARC support in their Microsoft 365 Roadmap, stating that “[ARC] is now enabled for Office 365 hosted mailboxes.” But at that time it could only be used between Office 365 tenants, or from Microsoft’s in-house services. However in June of 2022 they made it possible for each tenant to […]

ARC (Authenticated Received Chain) is an email authentication mechanism, sort of. The point of ARC is to encapsulate a check of email authentication results and include it in forwarded mail.If I receive email at an address, then I forward mail to another address, authentication results are difficult for the mail server at the second receiving site to interpret correctly. SPF works on a “last hop” methodology, meaning that a server doing an SPF check can only check the server that just connected to it — making it incompatible with email forwarding, because email forwarding involves more servers and thus more “hops.” A DKIM authentication signature is supposed to be compatible with email forwarding, but there are enough glitches out in the wild — encoding problems, rewriting headers for forwarding (or adding headers or footer text for mailing lists) that it just doesn’t work perfectly 100% of the time. And then

The Japan Anti-Abuse Working Group (JPAAWG) held its second annual meeting in Tokyo, Japan on November 14th and 15th, 2019. DMARC.org director Steve Jones was invited to give a general update on DMARC and related matters, and the slides from that presentation are now available for download (with notes). The update covers a number of areas, including two new publications from the […]

The Authenticated Received Chain (ARC) was designed to address situations where email messages that are forwarded, and in some cases altered, will no longer pass email authentication checks. After spending 3 years as a work item in the IETF‘s DMARC Working Group, the specification was published as RFC 8617 (HTML, PDF, plain text) on July […]

The Japan Anti-Abuse Working Group (JPAAWG) held its first meeting in Tokyo, Japan on November 8th, 2018. DMARC.org director Steve Jones was invited to give a general update on DMARC and related matters, and the slides from that presentation are now available for download. The update covers several areas of interest to people working to […]