Thanks for that, the only minor query l have now is which bit of the code l need to delete so that the sender does not receive a receipt email.
Is this the coding l need to delete?

// email variable not set - load $valid_ref1 page
if (!isset($_POST['email']))
{
echo "<script language=\"JavaScript\"><!--\n ";
echo "top.location.href = \"$valid_ref1\"; \n// --></script>";
exit;
}