An auto-responder is a predefined email message, that's sent automatically as an answer to each email received inside a mailbox with this option enabled. The two most typical examples for using this feature are automatic e-mails that one is briefly out of the workplace or that an order is received successfully. An auto-responder can also be used as a common verification that an email is delivered successfully, which can be something rather important in enterprise email correspondence. The message that is sent can contain pretty much anything and can be altered with respect to the conditions and exactly what the auto-responder will be employed for. As the option is enabled server-side, there isn’t anything you need to do manually and you don't need an email program to be active at all times for an automatic reply to be delivered to the person sending you an e-mail.