pct tag
A DMARC tag from RFC 7489 asking receivers to apply the policy to only a percentage of failing mail; RFC 9989 retired it as historic.
What it means
pct took a value from 0 to 100 (default 100) and was meant for gradual rollout, for example p=quarantine; pct=25. RFC 9989 explains why it was dropped: receivers applied in-between values inconsistently, and only 0 and 100 behaved predictably. pct=0 had acquired a useful side effect, prompting some mailing lists and forwarders to rewrite the From address, so that behaviour moved to the new t= tag (t=y corresponds to pct=0).
IANA now lists pct as historic. Receivers built on RFC 7489 still read it, and Google's setup guide still describes it and requires pct=100 (or no pct) for BIMI.
New records should leave it out or use t= for testing.
Example
v=DMARC1; p=quarantine; pct=100Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- RFC 9989: Domain-based Message Authentication, Reporting, and Conformance (DMARC), appendix A.6rfc-editor.org
- IANA: DMARC parameters registryiana.org
- Google Workspace Admin Help: Set up DMARCknowledge.workspace.google.com
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