I'm having a similar problem as above. I have a sign-up form as a plug-in placed on the index page. It can be viewed here: neprugby.us It works perfectly except for the redirect to my thankyou.php page. The email is sent as expected, but it always redirects to the following directory (resulting in a 404 error): thankyou.php
The sign-up form plug-in code is attached. I've tried redirecting to both 'thankyou.php' as well as '../thankyou.php' Any help is much appreciated.