NAME
    Mail::Header - manipulate mail RFC822 compliant headers

SYNOPSIS
        use Mail::Header;
    
        $head = new Mail::Header;
        $head = new Mail::Header \*STDIN;
        $head = new Mail::Header [<>], Modify => 0;

DESCRIPTION
    This package provides a class object which can be used for reading,
    creating, manipulating and writing RFC822 compliant headers.

CONSTRUCTOR
    new ( [ ARG ], [ OPTIONS ] )
        "ARG" 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

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

        MailFrom
                This option specifies what to do when a header in the form
                `From ' 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.

        FoldLength
                The default length of line to be used when folding header
                lines

METHODS
    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.

    mail_from ( OPTION )
        "OPTION" 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.

    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.

        The fold length for the tag that is begin processed

        The default fold length for the tag that is being processed

        The default fold length for the object

    extract ( ARRAY_REF )
        Extract a header from the given array. "extract" will modify this
        array. Returns the object that the method was called on.

    read ( FD )
        Read a header from the given file descriptor.

    empty ()
        Empty the "Mail::Header" object of all lines.

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

    header_hashref ( [ HASH_REF ] )
        As "header", but it will eventually set headers from a hash
        reference, and it will return the headers as a hash reference.

        The values in the hash might either be a scalar or an array
        reference, as an example:

            $hashref->{From}='Tobias Brox <tobix@cpan.org>';
            $hashref->{To}=['you@somewhere', 'me@localhost'];

    add ( TAG, LINE [, INDEX ] )
        Add a new line to the header. If "TAG" is *undef* the 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.

    replace ( TAG, LINE [, INDEX ] )
        Replace a line in the header. If "TAG" is *undef* the 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.

    combine ( TAG [, WITH ] )
        Combine all instances of "TAG" into one. The lines will be joined
        togther with "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.

    get ( TAG [, INDEX ] )
        Get the text form a line. If "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 "TAG" will
        be returned. In a scalar context the text for the first instance
        will be returned.

    delete ( TAG [, INDEX ] )
        Delete a tag from the header. If "INDEX" id given then the Nth
        instance of the tag will be removed. If "INDEX" is not given all
        instances of tag will be removed.

    count ( TAG )
        Returns the number of times the given atg appears in the header

    print ( [ FD ] )
        Print the header to the given file descriptor, or "STDOUT" if no
        file descriptor is given.

    as_string ()
        Returns the header as a single string.

    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.

    tags ()
        Retruns 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.

    dup ()
        Create a duplicate of the current object.

    cleanup ()
        Remove any header line that, other than the tag, only contains
        whitespace

    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.

AUTHOR
    Graham Barr <gbarr@pobox.com>

COPYRIGHT
    Copyright (c) 1995-7 Graham Barr. All rights reserved. This program is
    free software; you can redistribute it and/or modify it under the same
    terms as Perl itself.

