DMARC lookup validates your real-time DMARC records and find problems in them. It fetches the records and run checks to see if it follows standard procedures and are valid or not.
DMARC Lookup tool queries a given domain's DMARC records and parses them to find any errors. This test tells any non-standard procedures followed while setting up your records. Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a policy distribution tool which enables the email owner to communicate domain-level policies and preferences for message validation, placement, and reporting.
DMARC records standardize how the email originator associates and authenticates the domain identifiers with the messages, handle message policies using them and report about those messages. The DMARC policy enables the strict handling of emails that fail the authentication checks such as SPF or DKIM. If other authentication methods fail, DMARC reports the receiver of an email about how to handle the incoming message such as junk it, or consider it spam otherwise.