If you add a "from" email address in the PHP mail() , it will use that instead of the
apache@server.domain.com
You will need to add it in the "headers"
Code:
<?php
$to = "someone@example.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.";
?>