Brief of email anti-spoofing technologies: SPF, DKIM, DMARC, SIDF, DK, ADSP

For a few years unhurriedly I have been discovering features to protect emails from spoofing. Here I briefly collect information about all current standards, their functionality and an example with one main domain and two subdomains. It is not a complete guide, please read the RFCs and special guides for each standard.

Standards

Acronym	Definition	Official website	RFC	IETF Status	Short description
SPF	Sender Policy Framework	http://www.open-spf.org/	RFC4408 RFC7208	Standards Track RFC	Defines who (which servers) could send emails from domain and what to do with “bad” emails. Works with «RFC5321.MailFrom» and «HELO» identities.
DKIM	Domain Keys Identified Message	http://opendkim.org	RFC6376 RFC4871	Standards Track RFC	Sign an email by private key to identify the sender.
DMARC	Domain-based Message Authentication, Reporting, and Conformance	https://dmarc.org	RFC7489	Informational RFC, Working Group	The policy that unites the SPF and DKIM to define what should do receivers with «bad» emails.
SIDF	Sender ID Framework	-	RFC4406 RFC4407	Experimental (2006)	Analog SPF, but works with «RFC5321.MailFrom» and «RFC5322.From».
ADSP	Author Domain Signing Practices	-	RFC5617	Historic (2014)	Extension to DKIM allowing domain owner to specify whether or not they signed all outgoing mail.
DK	DomainKeys	http://domainkeys.sourceforge.net	RFC4870	Historic	Analog of DKIM. This standard was superseded by DKIM (RFC4871).