DMARC sp= Tag — Subdomain Policy (sp)

The DMARC sp tag sets a separate policy for subdomains that don't have their own DMARC record. Without it, subdomains inherit the parent's p= policy.

Importance
Recommended
Tag
sp=
Default
Inherits from p
Example
sp=none

✅ Valid Values

none No enforcement for subdomains. Useful when subdomains send legitimate mail you haven't fully audited.
quarantine Quarantine failing subdomain mail.
reject Reject failing subdomain mail.

💬 What This Tag Does

The "sp" tag lets you apply a different policy to subdomains that don't have their own DMARC record. If omitted, subdomains inherit the parent domain's "p" policy. This is useful when you want strict policy on your root domain but need to allow subdomains more flexibility, or vice versa.

📚 RFC References

↗RFC 7489 §6.3 — DMARC Record Format

🔗 Related DMARC Tags

p=
Policy (p)

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