DMARC is a DNS-published email policy that tells receiving servers what to do with messages that fail authentication: monitor them (`p=none`), send them to spam or quarantine (`p=quarantine`), or reject them (`p=reject`). It is published at `_dmarc.yourdomain.com`. A missing DMARC record makes your domain easier to spoof and your marketing email is more likely to land in spam, and a `p=none` record only monitors. It does not enforce anything.
Also known as
v=DMARC1; p=none; p=quarantine; p=reject; DMARC record
In practice
DMARC is checkable from outside the domain, and it’s missing or left on p=none for a surprising share of commercial senders, which makes it a fast, high-impact fix. Roll it out in order: p=none to collect reports, then quarantine, then reject. Only tighten once every legitimate sending source is aligned with SPF and DKIM, or you’ll start blocking your own mail.
Related
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