header

{
'received'          => true,
'resent-date'       => true,
'resent-from'       => true,
'resent-sender'     => true,
'resent-to'         => true,
'resent-cc'         => true,
'resent-bcc'        => true,
'resent-message-id' => true,
'comments'          => true,
'keywords'          => true