If you want to use an opt-in form on your site to start building a list of subscribers, you NEED an autoresponder. We, along with the majority of big name internet marketers, use Aweber.

How To Create A New List In Aweber

How To Create Your First Follow On Message In Aweber

How To Create a Form In Aweber. Part 1

How To Create a Form In Aweber. Part 2

All About Awebers Verified Opt-In

How To Organise Your Lists In Aweber

How To Automate Aweber