An auto-responder is usually a predefined email, which can be sent automatically as a reply to each e-mail received in a mailbox with this feature enabled. Two of the most typical cases for employing this option are automated e-mails that one is briefly out of the office or that an order is received successfully. An auto-responder may also be used as a general verification that the e-mail has been delivered successfully, which may be something very important in business communication. The message that is sent can contain more or less anything and could be modified based on the conditions and what the auto-responder will be employed for. As the feature is activated server-side, there isn’t anything you need to do manually and you do not need an e-mail application to be active constantly for the automatic reply to be mailed to the person sending you an e-mail.