Maybe this is not going to be an exact science even though it works for me at my host. This is exactly as it is in my files for one of the working sites. I have even pasted in the "non code" info to show exactly ...
contact.php
Code:
<?php
/**
* @version $Id: registration.php 2323 2006-02-12 19:06:40Z stingrey $
* @package Joomla
* @copyright Copyright (C) 2005 Open Source Matters. All rights reserved.
* @license http://www.gnu.org/copyleft/gpl.html GNU/GPL, see LICENSE.php
* Joomla! is free software. This version may have been modified pursuant
* to the GNU General Public License, and as distributed it includes or
* is derivative of works licensed under the GNU General Public License or
* other free or open source software licenses.
* See COPYRIGHT.php for copyright notices and details.
*/
ini_set("sendmail_from", "root@kpmuktaxis.com");
registration.php looks the same, these are the very first entries in the file. The address must be valid and you must put a valid address in Admin section where you have also selected php as the mail delivery option.