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Glossary

DMARC

DMARC is a DNS record that tells receiving servers what to do with a message that fails SPF and DKIM checks for the domain in its From address, and where to send reports about it.

Updated · By Otman Ounana · How we research

Why it matters when you send from your own Gmail

DMARC builds on both DKIM and SPF.[1] Its policy is one of three: none (only report), quarantine (treat as suspicious) or reject. For a cold emailer the practical value is the reports, which show who else is sending as your domain, and the protection against someone forging it. Start at none, read the reports, and tighten only when legitimate mail passes.

Example

A starting record is v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com. It changes nothing about delivery, and it starts the daily reports.

What to do

Publish a record with the policy set to none and a reporting address, then read the reports for a few weeks. Tighten the policy only once every service that sends as your domain, such as invoicing or a newsletter tool, passes.

Related terms

All terms are on the glossary.

Read next

  • The 5,000-a-day bulk sender ruleWho Google counts as a bulk sender, what counts toward 5,000, why it is permanent, and the arithmetic for someone sending cold email from their own mailbox.
  • Gmail 550 5.7.1 errorsGmail's 550 5.7.1 bounce has more than a dozen meanings. The ones a person sending from their own mailbox meets, quoted from Google's error list, with the fix for each.
  • DMARC checkerFree DMARC, SPF and DKIM checker. Enter a domain to see each record explained in plain words: policy, reports, SPF lookups and what to fix. Runs in your browser.
  • MX recordAn MX (mail exchanger) record is a DNS entry that names the servers which accept incoming mail for a domain.

Sources

  1. DMARC.org, Overview. “DMARC builds upon both the DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) specifications.” Read on 1 October 2026.