NAME
dmarc_lookup: look up DMARC policy for a domain
SYNOPSIS
dmarc_lookup example.com [ --verbose ]
DESCRIPTION
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 Organizational Domain, this is roughly equivalent to the following commands:
dig +short _dmarc.example.com TXT
$_
->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.].
EXAMPLES
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:
SEE ALSO
AUTHORS
Matt Simerson <msimerson@cpan.org>
Davide Migliavacca <shari@cpan.org>
Marc Bradshaw <marc@marcbradshaw.net>