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Mail::DKIM::AuthorDomainPolicy - represents an Author Domain Signing Practices (ADSP) record


version 1.20220520


The Author Domain Signing Policies (ADSP) record can be published by any domain to help a receiver know what to do when it encounters an unsigned message claiming to originate from that domain.

The record is published as a DNS TXT record at _adsp._domainkey.DOMAIN where DOMAIN is the domain of the message's "From" address.

More details about this record can be found by reading the specification itself at



Lookup an ADSP record in DNS.

  my $policy = Mail::DKIM::AuthorDomainPolicy->fetch(
            Protocol => 'dns',
            Author => '',

If the ADSP record is found and appears to be valid, an object containing that record's information will be constructed and returned. If the ADSP record is blank or simply does not exist, an object representing the default policy will be returned instead. (See also "is_implied_default_policy()".) If a DNS error occurs (e.g. SERVFAIL or time-out), this method will "die".


Construct a default policy object.

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


Construct an ADSP record from a string.

  my $policy = Mail::DKIM::AuthorDomainPolicy->parse(
          String => 'dkim=all',
          Domain => 'aaa.example',



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. It can be considered very suspicious.


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

Note: in the future, these values may become: none - no ADSP record is published pass - a passing signature is present fail - ADSP record is "all" and no passing signature is found discard - ADSP record is "discardable" and no passing signature is found nxdomain - the DNS domain does not exist temperror - transient error occurred permerror - non-transient error occurred


Tells whether 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.


Tells where the policy was fetched from.

If the policy is domain-wide, this will be domain where the policy was published.

If the policy is user-specific, TBD.

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


Get or set the outbound signing policy (dkim=) tag.

  my $sp = $policy->policy;

Outbound signing policy for the entity. Possible values are:


The default. The entity may sign some or all email.


All mail from the domain is expected to be signed, using a valid Author signature, but the author does not suggest discarding mail without a valid signature.


All mail from the domain is expected to be signed, using a valid Author signature, and the author is so confident that non-signed mail claiming to be from this domain can be automatically discarded by the recipient's mail server.


The domain is out of scope, i.e., the domain does not exist in the DNS.


True if policy is "all".


True if policy is "strict".


  • Section 4.3 of the specification says to perform a query on the domain itself just to see if it exists. This class is not currently doing that, i.e. it might report NXDOMAIN because is nonexistent, but it should not be treated the same as being nonexistent.


  • 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.