An auto-responder is usually a predefined email, which can be sent automatically as an answer to every email received in a mailbox with this option enabled. Two of the most typical instances for taking advantage of this option are automated e-mails that one is temporarily out of the office 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 quite important in business communication. The message that is sent can be more or less anything and can be altered depending on the circumstances and what the auto-responder will be employed for. As the feature is activated server-side, there isn’t anything you are required to do by hand and you do not need an email app to be enabled constantly for an automatic reply to be delivered to the person sending you an email.