Email authentication, or validation, is a collection of techniques aimed at providing verifiable information about the origin of email messages by validating the domain ownership of any message transfer agents (MTA) who participated in transferring and possibly modifying a message.
The Simple Mail Transfer Protocol (SMTP) has no such feature, so forged sender addresses in emails (email spoofing) have been widely used in phishing, email spam, and various types of frauds. To combat this, many competing email authentication proposals have been developed, but only fairly recently have three been widely adopted – SPF, DKIM and DMARC. The results of such validation can be used in automated email filtering, or can assist recipients when selecting an appropriate action.
- Email authentication (Wikipedia)
Domain-based Message Authentication, Reporting and Conformance (DMARC)
- DMARC (Wikipedia)
Check DMARC configuration
DMARC Check Tool – Check DMARC Records for Errors (MX toolbox)