An autoresponder is a series of letters written to be sent regularly over the Internet to a group of subscribers who are ready and willing to receive them.
You need to set up a system through which your subscribers can “opt-in” to the list. That is, the subscribers click a subscription link expressing a desire that they indeed would like to receive your emails. Otherwise you’d be sending spam which is not legal.
The best autoresponder list is a “double opt-in” list. In this method the subscriber not only clicks a subscription link but he or she then has to go and confirm the subscription by giving a positive reply to an opt-in email sent specifically for that purpose.
Why double opt-in? That prevents you getting subscribed to a list by someone else and without your knowledge and consent.
Here are couple important rules to create a great series of autoresponder letters: