I have this simple mail function in php:

<?php
$to = "husseincharania@yahoo.com";
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "someonelse@example.com";
$headers = "From: $from";
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
?>

But in my mail log I get the error:
"Recipient addresses must be specified on the command line or via the -t option
"
Any ideas on how I need to configure postfix to use this mail function?

Thanks a lot