You could try something like
PHP Code:
// build up Mail instance above
$recipients = array();
// add recipients into array
$recipients[] = 'me@mydomain.com';
// ...
foreach($recipients as $recipient) {
if(PEAR::isError($result = $mail->send($recipient, $headers, $body)) {
// log not sent, or how ever you handle the fact they are not sent
echo $result->getMessage();
}
}