DMARC sp — Subdomain policy
A separate policy for subdomains.
- Required
- no
- Default
- inherits p
- Valid values
none | quarantine | reject
What it does
Without sp, subdomains inherit whatever p says. Publishing sp=none while p=reject is a common and dangerous mistake: it leaves every subdomain of your domain spoofable, and attackers specifically look for it. Only set sp when a subdomain genuinely needs a weaker policy during migration.
Example
v=DMARC1; p=reject; sp=reject; rua=mailto:dmarc@example.com