dmarc_lookup - look up DMARC policy for a domain

       •   Matt Simerson <msimerson@cpan.org>

       •   Davide Migliavacca <shari@cpan.org>

       •   Marc Bradshaw <marc@marcbradshaw.net>

perl v5.38.2                                       2024-08-21                                   DMARC_LOOKUP(1p)

       Query the DNS for a DMARC policy for a (sub)domain. Displays any found results as the DNS record as a
       perl object. In the simplest case, where the domain name in the email From header matches the
       OrganizationalDomain, this is roughly equivalent to the following commands:

           dig +short _dmarc.example.com TXT

           print $_->txtdata."\n"
             for Net::DNS::Resolver->new(dnsrch=>0)->send('_dmarc.example.com','TXT')->answer;

       When the domain name in the email From header (header_from) is not an Organizational Domain (ex:
       www.example.com), an attempt is made to determine the O.D. using the Mozilla Public Suffix List. When the
       O.D. differs from the header_from, a second DNS query is sent to _dmarc.[O.D.].

       A DMARC record in DNS format looks like this:

       v=DMARC1; p=reject; adkim=s; aspf=s; rua=mailto:dmarc@example.com; pct=100;

       DMARC records are stored as TXT resource records in the DNS, at _dmarc.example.com.

       Other ways to retrieve a DMARC record for a domain are:

       dmarc_lookup - look up DMARC policy for a domain

       Mail::DMARC::Policy

          dmarc_lookup example.com [ --verbose ]