There are numerous options available for setting up newsletter registraton modules and newsletter management components for websites. Along the right column of this page are seen several that are available to be implemented on a Joomla CMS website. There are commercial components available beyond those shown here.
To get a little more insight into a few that I've evaluated please visit my blog entry at: Selecting a newsletter registration component for Joomla 1.5
Please feel free to test them. None are implemented, meaning that registering wll not add you to a mailing list, but they are set up to email you the double opt-in confirmation message.
