An auto-responder email is a an e-mail which is sent from your email address as a reply to every e-mail that you get. The message is predetermined and it is sent automatically, so every single person that contacts you via e-mail will get it once their message is received on the host that manages your email messages. This function is used when you have to inform people about different things, like being out of the office for a given time period or that an purchase has been received and is currently being prepared. The auto-responder email also serves as a confirmation for anyone who contact you that their message has been received, even if you're unable to read it and get back to them straight away. It can include virtually any text of your choice and it can be edited with respect to the exact occasion.