An auto-responder is usually a predefined e-mail, that's sent automatically as an answer to every email received in a mailbox with this function enabled. The two most common instances for employing this function are automatic email messages that one is briefly out of the workplace or that an order is received successfully. An auto-responder could also be used as a common verification that an e-mail is delivered successfully, which may be something very important in business communication. The message that is delivered can contain more or less anything and can be modified with respect to the conditions and what the auto-responder will be used for. As the function is enabled server-side, there isn’t anything you are expected to do by hand and you do not need an email program to be enabled at all times for an automatic reply to be sent to the person sending you an email.