---
name: "Courier::Filter::Module::Header"
section: "3pm"
platform: "linux"
package: "courier-filter-perl"
version: "0.200+ds-6"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Courier::Filter::Module::Header"
---

# Courier::Filter::Module::Header(3pm)

Message header filter module for the Courier::Filter framework

## NAME

Courier::Filter::Module::Header - Message header filter module for the Courier::Filter framework

## SYNOPSIS

```
    use Courier::Filter::Module::Header;
    my $module = Courier::Filter::Module::Header->new(
        fields      => \%patterns_by_field_name,
        response    => $response_text,
        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.  It matches a message if one of the message's header fields matches the configured criteria.

### Constructor

The following constructor is provided:

- **new(%options)**: returns *Courier::Filter::Module::Header*

  Creates a new **Header** filter module.

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

  - **fields**

    *Required*.  A reference to a hash containing the message header field names and patterns (as key/value pairs) that messages are to be matched against. Field names are matched case-insensitively.  Patterns may either be simple strings (for exact, case-sensitive matches) or regular expression objects created by the `"qr//"` operator (for inexact, partial matches).

    So for instance, to match any message from the "debian-devel" mailing list with the subject containing something about 'duelling banjoes', you could set the `"fields"` option as follows:

    ```
        fields      => {
           'list-id'    => '<debian-devel.lists.debian.org>',
            subject     => qr/duell?ing\s+banjoe?s?/i
        }
    ```

  - **response**

    A string that is to be returned literally as the match result in case of a match.  Defaults to **"Prohibited header value detected: \<field\>: \<value\>"**.

  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::Envelope, Courier::Filter::Module, Courier::Filter::Overview.

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

## AUTHOR

Julian Mehnle \<julian@mehnle.net\>