DMARC Checker

What is checked

The tool looks up a DMARC record the same way mail servers do per RFC 7489: on the _dmarc name of the domain itself. A subdomain without its own record inherits the record of the parent domain. Every tag in the record is explained in plain words. The tool also flags the errors that make receivers skip a record: multiple records on the same name, a lowercase version tag, an invalid policy, and a duplicated tag.

Report addresses are checked too. If an address belongs to a different domain, that domain's owner must confirm acceptance of the reports with their own record; otherwise the reports will never arrive.

SPF and DKIM

DMARC counts a message as passing when the SPF check or the DKIM signature passes for the domain in the From field. That is why the tool also checks the SPF record along with its DNS lookup count, and the DKIM keys. Keys are searched through common selectors. You can enter your own selector in the field: it appears in the DKIM-Signature header of a message after s=.

Requirements of mail providers

Since February 2024, Gmail requires SPF, DKIM, and DMARC from senders of more than 5000 messages per day, and Yahoo requires the same from bulk senders. Outlook.com follows since May 2025. Yandex Mail names DKIM and SPF as mandatory and recommends DMARC. DNS shows whether the records exist, but whether the domains match can only be verified from message headers.