What your DMARC record tells receivers
DMARC connects the two technical checks, SPF and DKIM, to the address people actually see in the From line. A message passes DMARC when at least one of them passes and is aligned with the From domain. Your record then tells receivers what to do with mail that fails, and where to send reports about it.
p=is the policy:nonemonitors,quarantinesends failures to spam,rejectblocks them.rua=lists where daily aggregate reports are sent. Without it you're flying blind.pct=applies the policy to a share of failing mail, which is useful while rolling out enforcement.adkim=andaspf=choose relaxed or strict alignment. Relaxed is the right default for almost everyone.
The safe path to p=reject
Jumping straight to p=reject can block your own invoices or newsletters if a service you use isn't set up yet. Start with p=none and a report address, read the reports until every legitimate sender passes, then step up through quarantine with a rising pct before switching to reject.
Need a record? Build one with the DMARC generator, or run a full domain health check to see SPF, DKIM and DMARC together.