OpenDMARC (Domain-based Message Authentication, Reporting & Conformance)
provides an open source library that implements the DMARC verification
service plus a milter-based filter application that can plug in to any
milter-aware MTA, including sendmail, Postfix, or any other MTA that supports
the milter protocol.
The DMARC sender authentication system is still a draft standard, working
towards RFC status.
The database schema required for some functions is provided in
/usr/share/opendmarc/db. The rddmarc tools are provided in