A system which automatically responds to e-mails. - An Auto-Responder is a special e-mail address which sends the user either one message, or a series of messages, in response to a request for more information.
In order to receive the information the user will either need to send a blank e-mail to a specific address, or fill out a form on a web page.
Auto-responders can be a powerful way to market, as some services allow you to make sure that the prospect sees the message more than once (follow-up auto-responders), or a series of different pitches. Innovative auto-responder uses including offering a free course or free information via e-mail, as part of a subtle pitch for a product or service.
A follow-up auto-responder service (which sends a series of messages) should of course allow a user to remove themselves at any point.