Deliverability
DMARC explained — without the acronym soup
What DMARC actually does, why the report files matter, and how to read a DMARC aggregate report in five minutes.
9 Feb 2026 6 min readBy Autocloz Editorial, Deliverability team
DMARC in one sentence
DMARC tells receiving mail servers what to do with mail that *claims* to be from your domain but cannot prove it (failed SPF or DKIM): reject it, quarantine it (spam folder), or do nothing (report only).
The three policy levels
- p=none — report only. Useful for the first 30 days while you fix breakages. Anything with p=none for more than two months is a hint nobody is reading the reports.
- p=quarantine — recipients route failing mail to spam.
- p=reject — recipients reject failing mail outright.
What a DMARC report file looks like
Each ISP that handles your mail emails you a daily ZIP of an XML file (RFC 7489). The file lists every IP that sent mail claiming your domain, and whether SPF/DKIM aligned.
Autocloz parses these for you and surfaces the misaligned senders in plain English.