An auto-responder is a predefined message, which can be sent automatically as an answer to every message received inside a mailbox with this feature activated. Two of the most common examples for employing this function are automatic email messages that one is temporarily out of the workplace or that an order has been received successfully. An auto-responder may also be used as a basic confirmation that an e-mail has been delivered successfully, which can be something rather important in business email correspondence. The message that is sent can be 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 activated server-side, there isn’t anything you are required to do manually and you don't need an e-mail app to be active at all times for the automatic reply to be sent to the individual sending you an email.