CODE EXAMPLE FOR PHP

how to redirect to another page in php after submit

Right after @mail($email_to, $email_subject, $email_message, $headers);

header('Location: nextpage.php');

Note that you will never see 'Thanks for subscribing to our mailing list'

That should be on the next page, if you echo any text you will get an error because the headers would have been already created, if you want to redirect never return any text, not even a space!