Use this DMARC lookup tool to find the DNS DMARC records of a domain online, from your web browser. DMARC (which stands for "Domain-based Message Authentication, Reporting & Conformance") is an email authentication protocol and describes the sender's email policy for any domain. Read more on DMARC.org website. For a quick test, type "debian-administration.org" in the form below (_dmarc. is pre-inserted):