[val@valcohen.com]

Smarty needs to have the value of the variable "hear" assigned to it -- it can't look it up directly.

You need something like

$mail_smarty->assign("hear",$customer.hear);

in the code that CALLS the history_order.tpl template

then in the template, {$hear} will echo the value passed to it.

Without passing a value, $hear is undefined (and likely empty), which is why you don't see its value in the output.

Does this help?