Authentication-Results header
The Authentication-Results header (RFC 8601) is a header a receiving mail server adds to a message recording the verdicts of its own SPF, DKIM, and DMARC checks -- pass, fail, softfail, or none -- along with identifying details like which domain and selector were checked. Downstream systems, such as a user's mail client, an anti-spam filter, or a later hop in a multi-server mail setup, can read this header to see what was already verified instead of repeating the same DNS lookups and cryptographic checks. Because any sender could forge this header on a message sent directly to a mailbox, receivers are expected to add it only at a trust boundary and strip or overwrite any instance a message already carried, so recipients inside that boundary can rely on it.
By AdminKit team, Netbase JSC · Updated