Julian Mehnle

NAME

Courier::Filter::Module::SPF - SPF filter module for the Courier::Filter framework

SYNOPSIS

    use Courier::Filter::Module::SPF;
    
    my $module = Courier::Filter::Module::SPF->new(
        scope               => 'mfrom' || 'helo',
        match_on            => ['fail', 'permerror', 'temperror'],
        default_response    => $default_response_text,
        spf_options         => {
            # any Mail::SPF::Server options
        },
        
        logger      => $logger,
        inverse     => 0,
        trusting    => 0,
        testing     => 0,
        debugging   => 0
    );
    
    my $filter = Courier::Filter->new(
        ...
        modules     => [ $module ],
        ...
    );

DESCRIPTION

This class is a filter module class for use with Courier::Filter. By default, it matches a message if the sending machine's IP address is not authorized to send mail from the envelope sender's (MAIL FROM) domain according to that domain's SPF (Sender Policy Framework) DNS record. This is classic inbound SPF checking.

The point of inbound SPF checking is for receivers to protect themselves against forged envelope sender addresses in messages sent by others.

Constructor

The following constructor is provided:

new(%options): returns Courier::Filter::Module::SPF

Creates a new SPF filter module.

%options is a list of key/value pairs representing any of the following options:

scope

A string denoting the authorization scope, i.e., identity, on which the SPF check is to be performed. Defaults to 'mfrom'. See "scope" in Mail::SPF::Request for a detailed explanation.

match_on

A reference to an array containing the set of SPF result codes which should cause the filter module to match a message. Possible result codes are pass, fail, softfail, neutral, none, permerror, and temperror. See the SPF specification for details on the meaning of those. If temperror is listed, a temperror result will by definition never cause a permanent rejection, but only a temporary one. Defaults to ['fail', 'permerror', 'temperror'].

Note: With early SPF specification drafts as well as the obsolete Mail::SPF::Query module, the permerror and temperror result codes were known as unknown and error, respectively; the old codes are now deprecated but still supported for the time being.

default_response

A string that is to be returned as the module's match result in case of a match, that is when the match_on option includes the result code of the SPF check (by default when a message fails the SPF check). However, this default response is used only if the (claimed) MAIL FROM or HELO domain does not provide a result explanation of its own. See "default_authority_explanation" in Mail::SPF::Server for more information.

SPF macro substitution is performed on the default response, just like on explanations provided by domain owners. If undef, Mail::SPF's default explanation will be used. Defaults to undef.

spf_options

A hash-ref specifying options for the Mail::SPF server object used by this filter module. See "new" in Mail::SPF::Server for the supported options. If any of Mail::SPF::BlackMagic's additional options, such as default_policy (best-guess) or tfwl (trusted-forwarder.org accreditation checking), are specified, a black-magic SPF server object will be created instead.

fallback_guess
trusted_forwarders

Deprecated. These options should now be specified as default_policy and tfwl keys of the "spf_options" option instead, although these legacy options will continue to work for the time being. Furthermore, due to the move from the obsolete Mail::SPF::Query module to the Mail::SPF reference implementation, the Mail::SPF::BlackMagic extension module is now required when using these non-standard options.

All options of the Courier::Filter::Module constructor are also supported. Please see "new" in Courier::Filter::Module for their descriptions.

Instance methods

See "Instance methods" in Courier::Filter::Module for a description of the provided instance methods.

SEE ALSO

Courier::Filter::Module, Courier::Filter::Overview, Mail::SPF.

For AVAILABILITY, SUPPORT, and LICENSE information, see Courier::Filter::Overview.

REFERENCES

SPF website (Sender Policy Framework)

http://www.openspf.org

SPF specification

http://www.openspf.org/Specifications

AUTHOR

Julian Mehnle <julian@mehnle.net>