OpenDMARC is an open source implementation of Domain-based Message
Authentication, Reporting & Conformance, or DMARC. It builds on the
successes of technologies such as DomainKeys Identified Mail (DKIM)
and the Sender Policy Framework (SPF) to create an infrastructure
that enforces policy on domain names that are visible to end users,
and creates a feedback framework for identifying and tracking
fraudulent use of domain names in email.

It includes a library for handling DMARC record parsing,
a database schema and tools for aggregating and processing transaction
history to produce DMARC reports, and a filter that ties it all together
with an MTA using the milter protocol.