RFC 7489: DMARC: Domain-based Message Authentication, Reporting, and Conformance
Ties SPF and DKIM together into a single policy record that instructs receivers how to handle failing messages.
spam prevention
RFC 8058: Signaling One-Click Functionality for List Email Headers
Defines the List-Unsubscribe-Post header enabling one-click unsubscribe, required by Google and Yahoo bulk sender rules since Feb 2024.
RFC 7208: Sender Policy Framework (SPF)
Defines which IP addresses are authorised to send mail for a domain via DNS TXT records.
RFC 4871: DomainKeys Identified Mail (DKIM) Signatures
Original DKIM specification. Obsoleted by RFC 6376 in 2011.
