Changing the headers to not show employer's email...

Any suggestions? I think this is where I need to change it, thanks!!

function job_posting_mail_alter(&$key, &$to, &$subject, &$body, &$from, &$headers) {
global $user;
// intercept and alter confirmation mail only
switch ($key) {
case 'confirmation':
$confirmation = 'Thank you for your interest in a career at our company. "'
."\n\n".'You don\'t need to do anything'
.' further with this message (except maybe save it for your records).';
$headers['Content-Type'] = 'text/plain; charset=UTF-8; format=flowed;';
$body = t('!message', array('!message' => $confirmation), $user->language);
break;
}
}