Glossary
Email authentication
ARC
Authenticated Received Chain — lets an intermediary record the authentication results it saw before modifying a message, so a later receiver can take that into account. Useful only if the later receiver trusts the intermediary.
Defined in RFC 8617.
Where this appears
The lessons that use this term, and what each is for.
Email Authentication FundamentalsForwarding, mailing lists, and the limits of each protocolPredict which of SPF and DKIM survives a given intermediary, and why.DKIM PractitionerWhat breaks a signature in transitName the intermediary responsible when a signature that was valid at send fails at delivery.DMARC PractitionerForwarding and mailing listsSeparate the mail you can fix from the mail nobody can, and say which is which.DMARC PractitionerARC, in practiceSay what an ARC chain changes for your mail, and what it does not entitle you to.