Send eMail on triggered events or over a period of time!
Autoresponders are sometimes called "sequential autoresponders", triggered emails or even drip campaigns. They are an email or a series of emails that are sent out on a schedule, or a triggered event.
Some examples of their use would be to send an email on a customer's birthday, or maybe one month after their purchase. You could also automatically send a series of marketing "touches" over time.
Autoresponders can be a very powerful tool for maintining contact with your customers, or "drip marketing" your product or service. Harness this automation for your business and also reap the rewards of powerful reports and analytics for all your eMarketing campaigns.