What exactly does this check?

It reads the public DNS TXT records for your domain: the SPF record (exactly one v=spf1, the include for your ESP, the lookup count under 10, and the all qualifier), the DMARC record at _dmarc.yourdomain (policy none/quarantine/reject, a reporting address, pct) and DKIM by probing common selectors used by newsletter platforms, plus any selector you enter. It reports only what DNS says.

My records pass but I still land in Promotions. Why?

Authentication decides whether Gmail trusts who sent the email. The Promotions tab is a content decision: heavy images, many tracked links, a template that looks like a campaign. Passing SPF, DKIM and DMARC is the floor. Promotions placement is fixed with plainer issues and by asking readers to reply once or drag you to Primary.

Why does DKIM show "not found" when my ESP says it is set up?

DKIM keys live under a selector name (like beehiiv._domainkey or k1._domainkey) and every platform uses its own. The tool probes the common ones. If yours is custom, find the selector in your ESP domain settings and enter it in the selector field.

Is DMARC p=none good enough?

It is the minimum Gmail and Yahoo require for bulk senders, so it passes. It does not protect the domain: mail that fails checks is still delivered. Once your reports look clean for a few weeks, move to p=quarantine, then p=reject.

Do you store the domains people check?

No. Lookups run against public DNS, results are returned to your browser, and nothing is stored. Requests are rate-limited per IP.

Free · No signup required

Free Email Domain Checker (SPF, DKIM, DMARC)

Newsletters landing in spam? Check the three DNS records first. Fixes are worded for beehiiv, Kit, Mailchimp, Substack, MailerLite, Brevo, Ghost and more.

Use the domain your newsletter is sent from (often a subdomain like news. or mail.), not your website if they differ.

Writesy AI — Free to start

Deliverability sorted? Now fix the Sunday.

This is the manual version. The Newsletter Studio does it every week from your sources: watches them, tells you what is new since your last issue, remembers what you covered, and lays the picks out with link, quote and your take.

No credit card required·30 free credits·Cancel anytime

Continue Your Workflow

Email Subject Line Tester

Test your email subject line for open rate potential. Get a score, spam word warnings, and AI-generated alternatives.

Newsletter Sponsorship Rate Calculator

Work out what to charge a newsletter sponsor from your subscribers, open rate and niche. Rate band per placement, package pricing and a media kit you can copy or print. No signup.

RSS Feed Finder

Paste any site and find its RSS or Atom feeds, discovered from the page and probed at the usual paths, then validated. Build a Google News search feed and turn Google Alerts into RSS. Sources for a curated newsletter, without 30 open tabs.

How to Use the Free Email Domain Checker (SPF, DKIM, DMARC)

1
Enter your input
Type or paste your content into the Email Domain Checker (SPF, DKIM, DMARC) input field above.
2
Get instant results
The tool uses AI to generate results — no waiting, no account needed.
3
Apply the insights
Copy your results, improve your content, or click through to Writesy AI to generate a complete piece from scratch.