DMARC record
The TXT record at _dmarc followed by the domain, beginning v=DMARC1, that carries a domain's DMARC policy and reporting addresses.
What it means
A DMARC record is published at _dmarc.example.com as a list of tag=value pairs separated by semicolons. v=DMARC1 must come first, or the whole record is ignored. Other tags under RFC 9989: p (policy), sp (existing subdomains), np (non-existent subdomains), adkim and aspf (alignment modes), rua and ruf (report addresses), fo (failure report options), t (test mode) and psd (public suffix flag). Unknown tags are ignored.
If two DMARC records exist at the same name, receivers discard both, as if none were published. A record without a valid p= is treated as p=none if it lists a valid rua address, and ignored otherwise; RFC 9989 makes p recommended where RFC 7489 required it.
When no record exists for the exact From domain, receivers look for one higher up (at the organizational domain), so one record at example.com normally covers mail.example.com too.
Example
v=DMARC1; p=reject; sp=reject; adkim=r; aspf=r; rua=mailto:dmarc@example.comRelated terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
All 432 terms in the glossaryThe wiki: blocklists and bounce codes