As others have said you can use explode to get the results into an array however, the problem with this approach is there is no guarantee the user will enter the information in the correct order.
What I would do is this. It's still not fool proof (And using separate inputs would be better) but it's better.
<?php
$textareastring = $_POST['textareaname'];
$array = explode("\n",$textareastring );
foreach($array as $value) {
$data = explode(',',$value);
if (strpos($data[1], '@'))
{
$name = $data[0];
$email = $data[1];
}else{
$name = $data[1];
$email = $data[0];
}
}
?>