The Newsletter option gives a page for your customers / users to automatically sign up or remove themselves from your newsletter list. The list is fully managed through your website. When you want to send a newsletter, you only need to email one address and your letter will automatically go out to everyone on your list. It is truely a no-hastle newsletter management system.
You can choose to recieve email notification when users sign up or remove their email, and your website shows you how many emails are currently on your newsletter list.