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Mail::Header(3)       User Contributed Perl Documentation      Mail::Header(3)
NAME
       Mail::Header - manipulate MIME headers
SYNOPSIS
        use Mail::Header;
        my $head = Mail::Header->new;
        my $head = Mail::Header->new( \*STDIN );
        my $head = Mail::Header->new( [<>], Modify => 0);
DESCRIPTION
       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.
METHODS
   Constructors
       $obj->dup()
           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.
       $obj->empty()
           Empty an existing "Mail::Header" object of all lines.
       $obj->extract(ARRAY)
           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.
           example:
            $fields->{From} = 'Tobias Brox <tobix AT cpan.org>';
            $fields->{To}   = ['you@somewhere', 'me@localhost'];
            $head->header_hashref($fields);
       $obj->read($fh)
           Read a header from the given file descriptor into an existing
           Mail::Header object.
   Accessors
       $obj->fold_length( [$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.
       $obj->mail_from('IGNORE'|'COERCE'|'KEEP'|'ERROR')
           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.
   Processing
       $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.
       $obj->as_string()
           Returns the header as a single string.
       $obj->cleanup()
           Remove any header line that, other than the tag, only contains
           whitespace
       $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.
       $obj->count($tag)
           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
           "chomp")
       $obj->print( [$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
           header.
       $obj->tags()
           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
           specified.
       $obj->unfold( [$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
           unfolded.
           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.
SEE ALSO
       This module is part of the MailTools distribution,
       http://perl.overmeer.net/mailtools/.
AUTHORS
       The MailTools bundle was developed by Graham Barr.  Later, Mark
       Overmeer took over maintenance without commitment to further
       development.
       Mail::Cap by Gisle Aas <aas AT oslonett.no>.  Mail::Field::AddrList by
       Peter Orbaek <poe AT cit.dk>.  Mail::Mailer and Mail::Send by Tim Bunce
       <Tim.Bunce AT ig.uk>.  For other contributors see ChangeLog.
LICENSE
       Copyrights 1995-2000 Graham Barr <gbarr AT pobox.com> and 2001-2017 Mark
       Overmeer <perl AT overmeer.net>.
       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.  See
       http://www.perl.com/perl/misc/Artistic.html
perl v5.26.3                      2018-01-22                   Mail::Header(3)