The pct tag was defined by the previous DMARC specification to sample application of a requested policy. RFC 9989 removed it, so it should not be used for a new rollout.
Use t=y instead. Test mode lowers the effective policy by one level: p=quarantine; t=y is effectively none, and p=reject; t=y is effectively quarantine. Analysis tools may still recognise pct in older records, but generators should not emit or recommend it.
Check it on your domain
- DMARC Checker: look up and validate a domain's DMARC record and policy.
- DMARC Generator: build a valid DMARC record from a simple form.
- DMARC Report Analyser: read a DMARC aggregate (RUA) report in plain English.