vDMARC1

vDMARC1 refers to the version tag used in DMARC DNS records to identify the version of the policy governing email authentication and reporting for a domain. The canonical form is v=DMARC1, which is placed as the first tag in a DNS TXT record published at the domain’s _dmarc subdomain (for example, _dmarc.example.com). Receiving systems read this tag to confirm that the record adheres to the DMARC specification before applying the associated policy and reporting instructions.

The v=DMARC1 tag does not perform authentication itself. DMARC relies on the results of SPF and DKIM and their alignment with the domain in question. The v tag simply signals that the record uses the DMARC specification, enabling parsers to interpret the rest of the tags correctly, such as p (policy), rua (aggregate reports), ruf (forensic reports), sp (subdomain policy), and other optional parameters like pct, rf, and ri.

In practice, an effective DMARC policy is published as a TXT record starting with v=DMARC1, followed by policy directives (for example, p=reject), reporting destinations (rua, ruf), and further options that control enforcement and reporting. The term vDMARC1 is sometimes used informally to refer to this concept, but the standard syntax requires v=DMARC1. If the v tag is missing or malformed, some receivers may treat the domain as not using DMARC, reducing the policy’s effectiveness.

In summary, vDMARC1 (specifically v=DMARC1) is the version identifier in DMARC records, ensuring that email receivers recognize and correctly process the domain’s DMARC policy.