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Mail::Header(3)	      User Contributed Perl Documentation      Mail::Header(3)

       Mail::Header - manipulate MIME headers

	use Mail::Header;

	my $head = Mail::Header->new;
	my $head = Mail::Header->new( \*STDIN );
	my $head = Mail::Header->new( [<>], Modify => 0);

       Read, write, create, and	manipulate MIME	headers, the leading part of
       each modern e-mail message, but also used in other protocols like HTTP.
       The fields are kept in Mail::Field objects.

       Be aware	that the header	fields each have a name	part, which shall be
       treated case-insensitive, and a content part, which may be folded over
       multiple	lines.

       Mail::Header does not always follow the RFCs strict enough, does	not
       help you	with character encodings.  It does not use weak	references
       where it	could (because those did not exist when	the module was
       written)	which costs some performance and make the implementation a
       little more complicated.	 The Mail::Message::Head implementation	is
       much newer and therefore	better.

	   Create a duplicate of the current object.

       $obj->new( [$source], [%options]	)
       Mail::Header->new( [$source], [%options]	)
	   The $source may be either a file descriptor (reference to a GLOB)
	   or a	reference to an	array. If given	the new	object will be
	   initialized with headers either from	the array of read from the
	   file	descriptor.

	   %options is a list of options given in the form of key-value	pairs,
	   just	like a hash table. Valid options are

	    -Option    --Default
	     FoldLength	 79
	     MailFrom	 'KEEP'
	     Modify	 false

	   FoldLength => INTEGER
	     The default length	of line	to be used when	folding	header lines.
	     See fold_length().

	   MailFrom => 'IGNORE'|'COERCE'|'KEEP'|'ERROR'
	     See method	mail_from().

	   Modify => BOOLEAN
	     If	this value is true then	the headers will be re-formatted,
	     otherwise the format of the header	lines will remain unchanged.

   "Fake" constructors
       Be warned that the next constructors all	require	an already created
       header object, of which the original content will be destroyed.

	   Empty an existing "Mail::Header" object of all lines.

	   Extract a header from the given array into an existing Mail::Header
	   object. "extract" will modify this array.  Returns the object that
	   the method was called on.

       $obj->header( [ARRAY] )
	   "header" does multiple operations. First it will extract a header
	   from	the ARRAY, if given. It	will then reformat the header (if
	   reformatting	is permitted), and finally return a reference to an
	   array which contains	the header in a	printable form.

       $obj->header_hashref( [HASH] )
	   As header(),	but it will eventually set headers from	a hash
	   reference, and it will return the headers as	a hash reference.


	    $fields->{From} = 'Tobias Brox <>';
	    $fields->{To}   = ['you@somewhere',	'me@localhost'];

	   Read	a header from the given	file descriptor	into an	existing
	   Mail::Header	object.

       $obj->fold_length( [$tag], [$length] )
	   Set the default fold	length for all tags or just one. With no
	   arguments the default fold length is	returned. With two arguments
	   it sets the fold length for the given tag and returns the previous
	   value. If only $length is given it sets the default fold length for
	   the current object.

	   In the two argument form "fold_length" may be called	as a static
	   method, setting default fold	lengths	for tags that will be used by
	   all "Mail::Header" objects. See the "fold" method for a description
	   on how "Mail::Header" uses these values.

	   This	specifies what to do when a `From ' line is encountered.
	   Valid values	are "IGNORE" - ignore and discard the header, "ERROR"
	   - invoke an error (call die), "COERCE" - rename them	as Mail-From
	   and "KEEP" -	keep them.

       $obj->modify( [$value] )
	   If $value is	false then "Mail::Header" will not do any automatic
	   reformatting	of the headers,	other than to ensure that the line
	   starts with the tags	given.

       $obj->add( $tag,	$line [, $index] )
	   Add a new line to the header. If $tag is "undef" the	tag will be
	   extracted from the beginning	of the given line. If $index is	given,
	   the new line	will be	inserted into the header at the	given point,
	   otherwise the new line will be appended to the end of the header.

	   Returns the header as a single string.

	   Remove any header line that,	other than the tag, only contains

       $obj->combine( $tag [, $with] )
	   Combine all instances of $tag into one. The lines will be joined
	   together $with, or a	single space if	not given. The new item	will
	   be positioned in the	header where the first instance	was, all other
	   instances of	$tag will be removed.

	   Returns the number of times the given atg appears in	the header

       $obj->delete( $tag [, $index ] )
	   Delete a tag	from the header. If an $index id is given, then	the
	   Nth instance	of the tag will	be removed. If no $index is given,
	   then	all instances of tag will be removed.

       $obj->fold( [$length] )
	   Fold	the header. If $length is not given, then "Mail::Header" uses
	   the following rules to determine what length	to fold	a line.

       $obj->get( $tag [, $index] )
	   Get the text	from a line. If	an $index is given, then the text of
	   the Nth instance will be returned. If it is not given the return
	   value depends on the	context	in which "get" was called. In an array
	   context a list of all the text from all the instances of the	$tag
	   will	be returned. In	a scalar context the text for the first
	   instance will be returned.

	   The lines are unfolded, but still terminated	with a new-line	(see

       $obj->print( [$fh] )
	   Print the header to the given file descriptor, or "STDOUT" if no
	   file	descriptor is given.

       $obj->replace( $tag, $line [, $index ] )
	   Replace a line in the header.  If $tag is "undef" the tag will be
	   extracted from the beginning	of the given line. If $index is	given
	   the new line	will replace the Nth instance of that tag, otherwise
	   the first instance of the tag is replaced. If the tag does not
	   appear in the header	then a new line	will be	appended to the

	   Returns an array of all the tags that exist in the header. Each tag
	   will	only appear in the list	once. The order	of the tags is not

       $obj->unfold( [$tag] )
	   Unfold all instances	of the given tag so that they do not spread
	   across multiple lines. If $tag is not given then all	lines are

	   The unfolding process is wrong but (for compatibility reasons) will
	   not be repaired: only one blank at the start	of the line should be
	   removed, not	all of them.

       This module is part of the MailTools distribution,

       The MailTools bundle was	developed by Graham Barr.  Later, Mark
       Overmeer	took over maintenance without commitment to further

       Mail::Cap by Gisle Aas <>.  Mail::Field::AddrList	by
       Peter Orbaek <>.  Mail::Mailer	and Mail::Send by Tim Bunce
       <>.  For other	contributors see ChangeLog.

       Copyrights 1995-2000 Graham Barr	<> and 2001-2017	Mark
       Overmeer	<>.

       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.  See

perl v5.32.0			  2019-05-21		       Mail::Header(3)


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