np= tag
The DMARC tag setting the policy for subdomains that do not exist in DNS, which attackers can otherwise invent to send spoofed mail.
What it means
Spoofers sometimes send from made-up subdomains such as billing-secure.example.com, which have no records at all. np= lets the owner ask receivers to reject such mail even while existing subdomains run a softer policy. A subdomain counts as non-existent when a DNS query for it returns NXDOMAIN.
np= first appeared in the experimental RFC 9091 (DMARC for public suffix domains) and became part of the main standard in RFC 9989. Without np=, non-existent subdomains get the sp= policy, or p= when sp= is absent.
Receivers that implement only RFC 7489 ignore np=, so it adds protection where supported and does no harm elsewhere.
Example
v=DMARC1; p=quarantine; sp=none; np=reject; 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