Question 1

What is a DMARC record?

Accepted Answer

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is an email validation protocol that builds upon SPF and DKIM. It allows domain owners to publish instructions on how receivers should handle emails that fail authentication.

Question 2

What is the difference between p=none, p=quarantine, and p=reject?

Accepted Answer

p=none is monitoring mode only and does not prevent spoofing. p=quarantine directs mailbox providers to deliver unauthenticated emails to the recipient spam folder. p=reject is the highest level of security, instructing providers to reject fraudulent emails entirely.

Question 3

How does DMARC inheritance work on subdomains?

Accepted Answer

If a subdomain (such as mail.example.com) does not publish its own _dmarc record, mailbox providers recursively query the organizational apex domain (example.com) using Public Suffix List rules.

DMARC Record Checker & Policy Analyzer