ok, to troubleshoot:
add the following code at line 1 to turn on error reporting:
go to the bindings panel and expand the WA Uploaded Files Global Status group and add the Debug info binding to the page.
change the following line:
$GoToPage = "thank-you.php";
$GoToPage = "";
so that it will not redirect after sending the email.
post back the debug info results after testing the email along with a copy of the