many SMTP servers require that the form address be a valid email address for your domain.
you may have to use a hard coded from address, if you go to the advanced from settings, you can use the dynamic email address for the reply to address.
The x-mailier is an optional setting, the port and path to pear amy or may not need to be entered, depends on the host.
on the email page, add the following at line 1 to turn on error reporting:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>
then on the thank you page, add this cod after the <body> tag:
<pre><?php @session_start(); var_dump($_SESSION); ?></pre>
this will write the session contents to the page, to let us know if the email was successfully sent to the SMTP server or not.