An auto-responder is usually a predefined email message, which is sent automatically as an answer to each e-mail received inside a mailbox with this function activated. Two of the most typical cases for using this option are automated e-mails that one is temporarily out of the workplace or that an order is received successfully. An auto-responder can also be used as a basic verification that an e-mail is delivered successfully, which is often something rather important in business communication. The message that's sent can be pretty much anything and could be modified based on the circumstances and exactly what the auto-responder will be employed for. As the function is enabled server-side, there isn’t anything you have to do by hand and you don't need an email program to be active constantly for an automatic reply to be mailed to the person sending you an email.