You're going to love auto-responders. It is one of the most powerful tools that you will ever use online.
First, let's talk about what an auto-responder does.
It sends a series of messages to your prospects automatically.
There are two ways auto-responders work:
1.) The first type of auto responder you would use with a lead capture page. When someone comes to your lead-capture page, that prospect is automatically entered into an auto-responder, which is loaded with a series of messages that will be mailed to your prospects. The database is only built from people that come to that lead capture page...you cannot upload leads.
Here is a company I've been using - aweber. I also like EZ Lead Capture as a secondary option to be able to create multiple capture pages in a flash.
2.) The second auto responder is the type where you can upload leads to you buy from a lead company.