An autoresponder is a software program that sends a 'canned' reply in response to a specific action. Typically, an email to an autoresponder's email address or a purchase through an online store. If someone sends an e-mail to an autoresponders e-mail address, it automatically and immediately e-mails this person the reply (a good example is the common "out of office reply"), and at the same time it also sends the incoming message to a designated recipient so they can reply to this e-mail message later on. Speaking in terms of web design, an autoresponder is usually designed to let a web visitor know their action was completed successfully.