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Mail::DKIM::DkPolicy - represents a DomainKeys Sender Signing Policy record


version 1.20240124


DomainKeys sender signing policies are described in RFC4870(historical). It is a record published in the message sender's (i.e. the person who transmitted the message) DNS that describes how they sign messages.


fetch() - fetch a sender signing policy from DNS

  my $policy = Mail::DKIM::DkPolicy->fetch(
                   Protocol => 'dns',
                   Sender => '',

The following named arguments are accepted:


always specify "dns"


the "author" of the message for which policy is being checked. This is the first email address in the "From" header. According to RFC 2822, section 3.6.2, the "From" header lists who is responsible for writing the message.


the "sender" of the message for which policy is being checked. This is the first email address in the "Sender" header, or if there is not a "Sender" header, the "From" header. According to RFC 2822, section 3.6.2, the "Sender" header lists who is responsible for transmitting the message.

Depending on what type of policy is being checked, both the Sender and Author fields may need to be specified.

If a DNS error or timeout occurs, an exception is thrown.

Otherwise, a policy object of some sort will be returned. If no policy is actually published, then the "default policy" will be returned. To check when this happens, use

  my $is_default = $policy->is_implied_default_policy;

new() - construct a default policy object

  my $policy = Mail::DKIM::DkPolicy->new;

parse() - gets a policy object by parsing a string

  my $policy = Mail::DKIM::DkPolicy->parse(
                   String => 'o=~; t=y'


apply() - apply the policy to the results of a DKIM verifier

  my $result = $policy->apply($dkim_verifier);

The caller must provide an instance of Mail::DKIM::Verifier, one which has already been fed the message being verified.

Possible results are:


The message is approved by the sender signing policy.


The message is rejected by the sender signing policy.


The message is neither approved nor rejected by the sender signing policy. It can be considered suspicious.

flags() - get or set the flags (t=) tag

A vertical-bar separated list of flags.

is_implied_default_policy() - is this policy implied?

  my $is_implied = $policy->is_implied_default_policy;

If you fetch the policy for a particular domain, but that domain does not have a policy published, then the "default policy" is in effect. Use this method to detect when that happens.

location() - where the policy was fetched from

DomainKeys policies only have per-domain policies, so this will be the domain where the policy was published.

If nothing is published for the domain, and the default policy was returned instead, the location will be undef.

note() - get or set the human readable notes (n=) tag

Human readable notes regarding the record. Undef if no notes specified.

policy() - get or set the outbound signing policy (o=) tag

  my $sp = $policy->policy;

Outbound signing policy for the entity. Possible values are:


The default. The domain may sign some (but not all) email.


The domain signs all email.

signall() - true if policy is /-"

testing() - checks the testing flag

  my $testing = $policy->testing;

If nonzero, the testing flag is set on the signing policy, and the verify should not consider a message suspicious based on this policy.


  • Jason Long <>

  • Marc Bradshaw <>

  • Bron Gondwana <> (ARC)


Work on ensuring that this module passes the ARC test suite was generously sponsored by Valimail (


  • Copyright (C) 2013 by Messiah College

  • Copyright (C) 2010 by Jason Long

  • Copyright (C) 2017 by Standcore LLC

  • Copyright (C) 2020 by FastMail Pty Ltd

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.6 or, at your option, any later version of Perl 5 you may have available.