While it's possible to manage sequential e-mail messages manually, doing so is both time-consuming and complicated. A Web-based service such as GetResponse can manage the process by sending messages on schedule, while helping to ensure you don't fall afoul of CAN-SPAM.
Creating an autoresponder message in GetResponse is straightforward. You complete a Web form by adding the e-mail subject, text, and time interval in days since the last message, then select options such as tracking clicks and any resulting sales.
You can sign up to GetResponse's free service to see if it meets your needs--but there are some limitations. For example, this basic service permits text e-mail only, restricts the number of autoresponders to five, and adds an advertisement to each message.
The GetResponse Pro service costs $18 per month, supports an unlimited number of autoresponders, handles HTML e-mail, and removes the advertising.
GetResponse supports the double opt-in subscription method that I described, which it calls Confirmed Opt-In. The service also offers additional e-mail services, such as broadcast mailing lists that do not feature autoresponders.
If you like the idea of using an e-mail list but don't require sequential autoresponders, read my earlier column, "Making Your Mailing List Work for You."