Domain-based Message Authentication, Reporting, and Conformance
DMARC is the final layer of email authentication. Without it, your domain can be spoofed in phishing. Google and Yahoo require DMARC for bulk senders.
What It Defines
DMARC ties SPF and DKIM together with a published DNS policy (p=none/quarantine/reject) and abuse reporting (rua/ruf addresses). Enables domain owners to specify how receivers should handle unauthenticated email.
Canonical (Normative)
Convenient (Practical)
The canonical publication point for finalized RFCs. If a protocol is standardized as an RFC, the RFC Editor text is the normative final reference. Published by the IETF, IRTF, IAB, and independent stream.
Related Specs
Without a correct SPF record, your domain's email will fail or be deferred by major receivers (Gmail, Outlook). Set correctly as part of basic email deliverability.
DKIM is required to pass DMARC. Without it, your email won't be trusted by major providers. Set up alongside SPF as part of any serious email configuration.
Every email your company sends or receives goes through SMTP. You need this to configure mail servers, debug delivery failures, and understand SPF/DKIM/DMARC.