The DMARC Record Lookup / DMARC Check is a diagnostic tool that will parse the DMARC Record for the queried domain name, display the DMARC Record, and run a series of diagnostic checks against the record. Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a mechanism for policy distribution by which an organization that is the originator of an email can communicate domain-level policies and preferences for message validation, disposition, and reporting.
DMARC Records standardize how mail originators associate and authenticate domain identifiers with messages, handle message policies using those identifiers, and report about mail using those identifiers. According to RFC 7489, the DMARC mechanism for policy distribution enables the strict handling of email messages that fail authentication checks, such as SPF and/or DKIM. If neither of those authentication methods passes, DMARC tells the receiver how to handle the message, such as junk it (quarantine) or reject the message entirely.