Why is a DMARC policy with p=reject necessary?

A DMARC policy of p=reject instructs receiving mail servers (Gmail, Microsoft 365, Yahoo) to immediately drop and delete any incoming emails claiming to be from your domain that fail cryptographic SPF/DKIM authentication.

Are my domain details uploaded or tracked?

Never. All string synthesis, RFC syntax linting, and DNS record generation run 100% locally in your device's browser memory (RAM).

SPF & DMARC Record Generator + DNS Security Linter

Policy Mode	Action on Spoofed Email	Security Level
`p=none`	Delivered normally to recipient inbox; only sends diagnostic report.	Low (Monitoring Phase)
`p=quarantine`	Delivered directly into the recipient's Spam / Junk folder.	Moderate Protection
`p=reject`	Instantly dropped and deleted at the gateway; recipient never sees it.	Maximum (Zero Spoofing)

Policy Mode

Action on Spoofed Email

Security Level

p=none

Delivered normally to recipient inbox; only sends diagnostic report.

Low (Monitoring Phase)

p=quarantine

Delivered directly into the recipient's Spam / Junk folder.

Moderate Protection

p=reject

Instantly dropped and deleted at the gateway; recipient never sees it.

Maximum (Zero Spoofing)

Why SPF and DMARC Are Essential for Domain Reputation

Email protocols originally lacked sender verification mechanisms, allowing anyone to send emails with forged "From" headers. Today, major email providers (Google Workspace, Yahoo, Microsoft 365) mandate valid SPF, DKIM, and DMARC records for domain deliverability.

1. The 10-Lookup Limit in SPF Records

The RFC 7208 standard restricts SPF evaluation to a maximum of 10 nested DNS lookups. Adding too many include: mechanisms causes receiving servers to throw a PermError, which breaks domain authentication and routes legitimate emails to spam.

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Frequently Asked Questions

Where do I paste these TXT records?

Open your DNS management console (Cloudflare, GoDaddy, Namecheap, or AWS Route 53) and create two new TXT records: one with Host @ for SPF, and one with Host _dmarc for DMARC.

Is my domain name sent to any external server?

Never. All record formatting, lookup calculations, and RFC linting execute 100% locally in your device's browser memory (RAM).

SPF & DMARC DNS Record Generator

DMARC Policy Comparison (p=none vs p=quarantine vs p=reject)