on the thank you page, I added the following code to write the session contents, the session includes the status of sending the email:
<?php @session_start(); var_dump($_SESSION); ?>
using my email address, the following status is returned:
["waue_grant_application_form_1_Log"]=> string(191) "Sending To: firstname.lastname@example.org... mail() [function.mail]: SMTP server response: 550 Requested action not taken: mailbox unavailable or not local - Failure
this means that in order to send to outside addresses, you will need to use the Pear mail for SMTP mail object and add authentication.
contact you host for details on whether they support pear mail