Freature Request: Form Success Page/Messages

When a user signs up for any email reach newsletters, they are greeted with a blank page reading only "Thank You" after completing the signup.

There is no link to return the user to the home page, there is no site navigation, or branding, or ads. 

When a user signs up for a newsletter, there should be an option to redirect them to a site page, or static page. 

This can be accomplished by adding a "Landing Page URL:" or "Thank You Page URL:" field to the Edit List dialog for individual campaigns.