=encoding utf8

=head1 NAME

Mail::Message::Replace::MailHeader - fake Mail::Header

=head1 INHERITANCE

 Mail::Message::Replace::MailHeader
   is a Mail::Message::Head::Complete
   is a Mail::Message::Head
   is a Mail::Reporter

=head1 SYNOPSIS

  # change
  use Mail::Internet;
  use Mail::Header;
  # into
  use Mail::Message::Replace::MailInternet;
  # in existing code, and the code should still work, but
  # with the Mail::Message features.

=head1 DESCRIPTION

This module is a wrapper around a L<Mail::Message::Head::Complete|Mail::Message::Head::Complete>,
which simulates a L<Mail::Header> object.  The name-space of that module
is hijacked and many methods are added.

Most methods will work without any change, but you should test your
software again.  Small changes have been made to L<fold_length()|Mail::Message::Replace::MailHeader/"Simulating Mail::Header">,
L<header_hashref()|Mail::Message::Replace::MailHeader/"Simulating Mail::Header">.

Extends L<"DESCRIPTION" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"DESCRIPTION">.

=head1 OVERLOADED

Extends L<"OVERLOADED" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"OVERLOADED">.

=over 4

=item overload: B<""> stringifaction

Inherited, see L<Mail::Message::Head/"OVERLOADED">

=item overload: B<bool> true/false

Inherited, see L<Mail::Message::Head/"OVERLOADED">

=back

=head1 METHODS

Extends L<"METHODS" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"METHODS">.

=head2 Constructors

Extends L<"Constructors" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"Constructors">.

=over 4

=item $class-E<gt>B<build>( [PAIR|$field], ... )

Inherited, see L<Mail::Message::Head::Complete/"Constructors">

=item $obj-E<gt>B<clone>( [@names|ARRAY|Regexps] )

Inherited, see L<Mail::Message::Head::Complete/"Constructors">

=item $class-E<gt>B<new>( [$arg], %options )

The C<$arg> is an array with header lines.
Improves base, see L<Mail::Message::Head/"Constructors">

 -Option    --Defined in         --Default
  FoldLength                       79
  MailFrom                         'KEEP'
  Modify                           false
  field_type  Mail::Message::Head  Mail::Message::Field::Fast
  message     Mail::Message::Head  undef
  modified    Mail::Message::Head  false

=over 2

=item FoldLength => $octets

=item MailFrom => 'IGNORE'|'ERROR'|'COERCE'|'KEEP'

How to handle the C<From > lines.  See L<mail_from()|Mail::Message::Replace::MailHeader/"Simulating Mail::Header">.

=item Modify => BOOLEAN

Reformat all header lines when they come in: change the folding.

=item field_type => CLASS

=item message => $message

=item modified => BOOLEAN

=back

=back

=head2 Attributes

Extends L<"Attributes" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"Attributes">.

=head2 The header

Extends L<"The header" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"The header">.

=over 4

=item $obj-E<gt>B<isDelayed>()

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<isEmpty>()

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<isModified>()

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<knownNames>()

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<message>( [$message] )

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<modified>( [BOOLEAN] )

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<nrLines>()

Inherited, see L<Mail::Message::Head::Complete/"The header">

=item $obj-E<gt>B<orderedFields>()

Inherited, see L<Mail::Message::Head/"The header">

=item $obj-E<gt>B<size>()

Inherited, see L<Mail::Message::Head::Complete/"The header">

=item $obj-E<gt>B<wrap>($integer)

Inherited, see L<Mail::Message::Head::Complete/"The header">

=back

=head2 Access to the header

Extends L<"Access to the header" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"Access to the header">.

=over 4

=item $obj-E<gt>B<add>( $line, [$index] )

Add a header line, which simply calls C<Mail::Message::Head::add()> on
the header for the specified C<$line>.  The C<$index> is ignored, the unfolded
body of the field is returned.
Improves base, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<addListGroup>($object)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<addResentGroup>($resent_group|$data)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<addSpamGroup>($object)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<count>($name)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<delete>( $tag, [$index] )

Delete the fields with the specified C<$tag>.  The deleted fields are
returned.  If no index is given, then all are removed.
Improves base, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<get>( $name, [$index] )

Get all the header fields with the specified C<$name>.  In scalar context,
only the first fitting C<$name> is returned.  Even when only one C<$name> is
specified, multiple lines may be returned in list context: some fields
appear more than once in a header.
Improves base, see L<Mail::Message::Head/"Access to the header">

=item $obj-E<gt>B<grepNames>( [@names|ARRAY|Regexps] )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<listGroup>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<names>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<print>( [$fh] )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<printSelected>($fh, <STRING|Regexp>, ...)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<printUndisclosed>( [$fh] )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeContentInfo>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeField>($field)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeFields>( <STRING|Regexp>, ... )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeFieldsExcept>( <STRING|Regexp>, ... )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeListGroup>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeResentGroups>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<removeSpamGroups>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<replace>( $tag, $line, [$index] )

Replace the field named C<$tag>. from place C<$index> (by default the first) by
the C<$line>.  When C<$tag> is C<undef>, it will be extracted from the C<$line> first.
This calls L<Mail::Message::Head::Complete::reset()|Mail::Message::Head::Complete/"Access to the header"> on the message's head.

=item $obj-E<gt>B<resentGroups>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<reset>($name, @fields)

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<set>( $field | $line | <$name, $body, [$attrs]> )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<spamDetected>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<spamGroups>( [$names] )

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<string>()

Inherited, see L<Mail::Message::Head::Complete/"Access to the header">

=item $obj-E<gt>B<study>( $name, [$index] )

Inherited, see L<Mail::Message::Head/"Access to the header">

=back

=head2 About the body

Extends L<"About the body" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"About the body">.

=over 4

=item $obj-E<gt>B<guessBodySize>()

Inherited, see L<Mail::Message::Head/"About the body">

=item $obj-E<gt>B<guessTimeStamp>()

Inherited, see L<Mail::Message::Head::Complete/"About the body">

=item $obj-E<gt>B<isMultipart>()

Inherited, see L<Mail::Message::Head/"About the body">

=item $obj-E<gt>B<recvstamp>()

Inherited, see L<Mail::Message::Head::Complete/"About the body">

=item $obj-E<gt>B<timestamp>()

Inherited, see L<Mail::Message::Head::Complete/"About the body">

=back

=head2 Internals

Extends L<"Internals" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"Internals">.

=over 4

=item $obj-E<gt>B<addNoRealize>($field)

Inherited, see L<Mail::Message::Head/"Internals">

=item $obj-E<gt>B<addOrderedFields>($fields)

Inherited, see L<Mail::Message::Head/"Internals">

=item $obj-E<gt>B<createFromLine>()

Inherited, see L<Mail::Message::Head::Complete/"Internals">

=item $obj-E<gt>B<createMessageId>()

Inherited, see L<Mail::Message::Head::Complete/"Internals">

=item $obj-E<gt>B<fileLocation>()

Inherited, see L<Mail::Message::Head/"Internals">

=item $obj-E<gt>B<load>()

Inherited, see L<Mail::Message::Head/"Internals">

=item $any-E<gt>B<messageIdPrefix>( [$prefix, [$hostname]|CODE] )

Inherited, see L<Mail::Message::Head::Complete/"Internals">

=item $obj-E<gt>B<moveLocation>($distance)

Inherited, see L<Mail::Message::Head/"Internals">

=item $obj-E<gt>B<setNoRealize>($field)

Inherited, see L<Mail::Message::Head/"Internals">

=back

=head2 Error handling

Extends L<"Error handling" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"Error handling">.

=over 4

=item $obj-E<gt>B<AUTOLOAD>()

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<notImplemented>()

Inherited, see L<Mail::Reporter/"Error handling">

=back

=head2 Cleanup

Extends L<"Cleanup" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"Cleanup">.

=over 4

=item $obj-E<gt>B<DESTROY>()

Inherited, see L<Mail::Reporter/"Cleanup">

=back

=head2 Access to the header

=head2 Simulating Mail::Header

=over 4

=item $obj-E<gt>B<as_string>()

Returns the whole header as one big scalar.
Calls L<Mail::Message::Head::Complete::string()|Mail::Message::Head::Complete/"Access to the header">.

=item $obj-E<gt>B<cleanup>()

Cleanup memory usage.  Not needed here.

=item $obj-E<gt>B<combine>( $tag, [$with] )

I do not see any valid reason for this command, so did not implement it.

=item $obj-E<gt>B<dup>()

Duplicate the header, which is simply L<clone()|Mail::Message::Head::Complete/"Constructors">.

=item $obj-E<gt>B<empty>()

Clean-out the whole hash. Better not use this (simply create another
header object), although it should work.

=item $obj-E<gt>B<exists>()

Returns whether there are any fields.

=item $obj-E<gt>B<extract>(\@lines)

Extract (and remove) header fields from the array.

=item $obj-E<gt>B<fold>( [$length] )

Refold all fields in the header, to C<$length> or whatever L<fold_length()|Mail::Message::Replace::MailHeader/"Simulating Mail::Header">
returns.

=item $obj-E<gt>B<fold_length>( [[$tag], $length] )

Returns the line wrap, optionally after setting it to C<$length>.  The
old value is returned.  The C<$tag> argument is ignored, because it is
silly to have different lines fold in different ways.  This method
cannot be called statically anymore.

=item $obj-E<gt>B<header>( [ARRAY] )

Extract the fields from the C<ARRAY>, if specified, and then fold the fields.
Returned is an array with all fields, produced via L<orderedFields()|Mail::Message::Head/"The header">.

=item $obj-E<gt>B<header_hashref>(HASH)

If you are using this method, you must be stupid... anyway: I do not want to
support it for now: use L<add()|Mail::Message::Replace::MailHeader/"Access to the header"> and friends.

=item $obj-E<gt>B<mail_from>( ['IGNORE'|'ERROR'|'COERCE'|'KEEP'] )

What to do when a header line in the form `From ' is encountered. Valid
values are C<IGNORE> - ignore and discard the header, C<ERROR> - invoke
an error (die), C<COERCE> - rename them as Mail-From and C<KEEP>
- keep them.

=item $obj-E<gt>B<modify>( [BOOLEAN] )

Refold the headers when they are added.

=item $obj-E<gt>B<read>($file)

Read the header from the C<$file>.
Improves base, see L<Mail::Message::Head/"Internals">

=item $obj-E<gt>B<tags>()

Returns all the names of fields, implemented by
L<Mail::Message::Head::Complete::names()|Mail::Message::Head::Complete/"Access to the header">.

=item $obj-E<gt>B<unfold>( [$tag] )

Remove the folding for all instances of C<$tag>, or all fields at once.

=back

=head2 The nasty bits

=over 4

=item $any-E<gt>B<isa>($class)

Of course, the C<isa()> class inheritance check should not see our
nasty trick.

=back

=head1 DETAILS

Extends L<"DETAILS" in Mail::Message::Head::Complete|Mail::Message::Head::Complete/"DETAILS">.

=head1 DIAGNOSTICS

=over 4

=item Error: bad Mail-From choice: '$pick'.

Cast by C<mail_from()>

=item Warning: cannot remove field $name from header: not found.

You ask to remove a field which is not known in the header.  Using
L<delete()|Mail::Message::Replace::MailHeader/"Access to the header">, L<reset()|Mail::Message::Head::Complete/"Access to the header">, or L<set()|Mail::Message::Head::Complete/"Access to the header"> to do the job will not result
in warnings: those methods check the existence of the field first.
Cast by C<removeField()>

=item Error: class $package does not implement method $method.

Fatal error: the specific C<$package> (or one of its superclasses) does not
implement this method where it should. This message means that some other
related classes do implement this method however the class at hand does
not.  Probably you should investigate this and probably inform the author
of the package.
Cast by C<notImplemented()>

=item Warning: field objects have an implied name ($name)

Cast by C<build()>

=back

=head1 SEE ALSO

This module is part of Mail-Message version 4.01,
built on December 13, 2025. Website: F<http://perl.overmeer.net/CPAN/>

=head1 LICENSE

For contributors see file ChangeLog.

This software is copyright (c) 2001-2025 by Mark Overmeer.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.