Provided by: libmail-dmarc-perl_1.20230215-1ubuntu1_all 
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NAME
Mail::DMARC - Perl implementation of DMARC
VERSION
version 1.20230215
SYNOPSIS
DMARC: Domain-based Message Authentication, Reporting and Conformance
my $dmarc = Mail::DMARC::PurePerl->new(
... # see the documentation for the "new" method for required args
);
my $result = $dmarc->validate();
if ( $result->result eq 'pass' ) {
...continue normal processing...
return;
};
# any result that did not pass is a fail. Now for disposition
if ( $result->evalated->disposition eq 'reject' ) {
...treat the sender to a 550 ...
};
if ( $result->evalated->disposition eq 'quarantine' ) {
...assign a bunch of spam points...
};
if ( $result->evalated->disposition eq 'none' ) {
...continue normal processing...
};
DESCRIPTION
This module is a suite of tools for implementing DMARC. It adheres to the 2013 DMARC
draft, intending to implement every MUST and every SHOULD.
This module can be used by...
• MTAs and filtering tools like SpamAssassin to validate that incoming messages are
aligned with the purported sender's policy.
• email senders, to receive DMARC reports from other mail servers and display them via
CLI and web interfaces.
• MTA operators to send DMARC reports to DMARC author domains.
When a message arrives via SMTP, the MTA or filtering application can pass in a small
amount of metadata about the connection (envelope details, SPF and DKIM results) to
Mail::DMARC. When the validate method is called, Mail::DMARC will determine if:
a. the header_from domain exists
b. the header_from domain publishes a DMARC policy
c. if a policy is published...
d. does the message conform to the published policy?
e. did the policy request reporting? If so, save details.
The validation results are returned as a Mail::DMARC::Result object. If the author domain
requested a report, it was saved to the Report Store. The Store class includes a SQL
implementation that is tested with SQLite, MySQL and PostgreSQL.
There is more information available in the $result object. See Mail::DMARC::Result for
complete details.
Reports are viewed with the dmarc_view_reports program or with a web browser and the
dmarc_httpd program.
Aggregate reports are sent to their requestors with the dmarc_send_reports program.
For aggregate reports that you have been sent, the dmarc_receive program will parse the
email messages (from IMAP, Mbox, or files) and save the report results into the Report
Store.
The report store can use the same database to store reports you have received as well as
reports you will send. There are several ways to identify the difference, including:
• received reports will have a null value for report_policy_published.rua
• outgoing reports will have null values for report.uuid and report_record.count
CLASSES
Mail::DMARC - the perl interface for DMARC
Mail::DMARC::Policy - a DMARC policy
Mail::DMARC::PurePerl - Pure Perl implementation of DMARC
Mail::DMARC::Result - the results of applying policy
Mail::DMARC::Report - Reporting: the R in DMARC
Mail::DMARC::Report::Send - send reports via SMTP & HTTP
Mail::DMARC::Report::Receive - receive and store reports from email, HTTP
Mail::DMARC::Report::Store - a persistent data store for aggregate reports
Mail::DMARC::Report::View - CLI and CGI methods for viewing reports
Mail::DMARC::libopendmarc <http://search.cpan.org/~shari/Mail-DMARC-opendmarc> - an XS
implementation using libopendmarc
METHODS
new
Create a DMARC object.
my $dmarc = Mail::DMARC::PurePerl->new;
Populate it.
$dmarc->source_ip('192.0.1.1');
$dmarc->envelope_to('recipient.example.com');
$dmarc->envelope_from('sender.example.com');
$dmarc->header_from('sender.example.com');
$dmarc->dkim( $dkim_verifier );
$dmarc->spf([
{ domain => 'example.com',
scope => 'mfrom',
result => 'pass',
},
{
scope => 'helo',
domain => 'mta.example.com',
result => 'fail',
},
]);
Run the request:
my $result = $dmarc->validate();
Alternatively, pass in all the required parameters in one shot:
my $dmarc = Mail::DMARC::PurePerl->new(
source_ip => '192.0.1.1',
envelope_to => 'example.com',
envelope_from => 'cars4you.info',
header_from => 'yahoo.com',
dkim => $dkim_results, # same format
spf => $spf_results, # as previous example
);
my $result = $dmarc->validate();
source_ip
The remote IP that attempted sending the message. DMARC only uses this data for reporting
to domains that request DMARC reports.
envelope_to
The domain portion of the RFC5321.RcptTo, (aka, the envelope recipient), and the bold
portion in the following example:
RCPT TO:<user@example.com>
envelope_from
The domain portion of the RFC5321.MailFrom, (aka, the envelope sender). That is the the
bold portion in the following example:
MAIL FROM:<user@example.com>
header_from
The domain portion of the RFC5322.From, aka, the From message header.
From: Ultimate Vacation <sweepstakes@example.com>
You can instead pass in the entire From: header with header_from_raw.
header_from_raw
Retrieve the header_from domain by parsing it from a raw From field/header. The domain
portion is extracted by get_dom_from_header, which is fast, generally effective, but also
rather crude. It has limits, so read the description.
dkim
If Mail::DKIM::Verifier was used to validate the message, just pass in the
Mail::DKIM::Verifier object that processed the message:
$dmarc->dkim( $dkim_verifier );
Otherwise, pass in an array reference. Each member of the DKIM array results represents a
DKIM signature in the message and consists of the 4 keys shown in this example:
$dmarc->dkim( [
{
domain => 'example.com',
selector => 'apr2013',
result => 'fail',
human_result=> 'fail (body has been altered)',
},
{
# 2nd signature, if present
},
] );
The dkim results can also be build iteratively by passing in key value pairs or hash
references for each signature in the message:
$dmarc->dkim( domain => 'sig1.com', result => 'fail' );
$dmarc->dkim( domain => 'sig2.com', result => 'pass' );
$dmarc->dkim( { domain => 'example.com', result => 'neutral' } );
Each hash or hashref is appended to the dkim array.
Finally, you can pass a coderef which won't be called until the dkim method is used to
read the dkim results. It must return an array reference as described above.
The dkim result is an array reference.
domain
The d= parameter in the DKIM signature
selector
The s= parameter in the DKIM signature
result
The validation results of this signature. One of: none, pass, fail, policy, neutral,
temperror, or permerror
human result
Additional information about the DKIM result. This is comparable to
Mail::DKIM::Verifier->result_detail.
spf
The spf method works exactly the same as dkim. It accepts named arguments, a hashref, an
arrayref, or a coderef:
$dmarc->spf(
domain => 'example.com',
scope => 'mfrom',
result => 'pass',
);
The SPF domain and result are required for DMARC validation and the scope is used for
reporting.
domain
The SPF checked domain
scope
The scope of the checked domain: mfrom, helo
result
The SPF result code: none, neutral, pass, fail, softfail, temperror, or permerror.
DESIGN & GOALS
Correct
The DMARC spec is lengthy and evolving, making correctness a moving target. In cases where
correctness is ambiguous, options are generally provided.
Easy to use
Providing an implementation of DMARC that SMTP utilities can utilize will aid DMARC
adoption.
The list of dependencies appears long because of reporting. If this module is used without
reporting, the number of dependencies not included with perl is about 5. See the [Prereq]
versus [Prereq / Recommends] sections in dist.ini.
Maintainable
Since DMARC is evolving, this implementation aims to be straight forward and easy to alter
and extend. The programming style is primarily OO, which carries a small performance
penalty but dividends in maintainability.
When multiple options are available, such as when sending reports via SMTP or HTTP, calls
should be made to the parent Send class to broker the request. When storing reports, calls
are made to the Store class which dispatches to the SQL class. The idea is that if someone
desired a data store other than those provided by perl's DBI class, they could easily
implement their own. If you do, please fork it on GitHub and share.
Fast
If you deploy this in an environment where performance is insufficient, please profile the
app and submit a report and preferably, patches.
SEE ALSO
Mail::DMARC on GitHub <https://github.com/msimerson/mail-dmarc>
2015-03 RFC 7489 <https://tools.ietf.org/html/rfc7489>
DMARC Best Current Practices <http://tools.ietf.org/html/draft-crocker-dmarc-bcp-03>
HISTORY
The daddy of this perl module was a DMARC module for the qpsmtpd MTA
<https://github.com/smtpd/qpsmtpd/blob/master/plugins/dmarc>.
AUTHORS
• Matt Simerson <msimerson@cpan.org>
• Davide Migliavacca <shari@cpan.org>
• Marc Bradshaw <marc@marcbradshaw.net>
CONTRIBUTORS
• Benny Pedersen <me@junc.eu>
• Jean Paul Galea <jeanpaul@yubico.com>
• Marisa Clardy <marisa@clardy.eu>
• Priyadi Iman Nurcahyo <priyadi@priyadi.net>
• Ricardo Signes <rjbs@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2023 by Matt Simerson.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.