An auto-responder email is an e-mail which is sent back automatically to everybody who sends a message to an e-mail address with this option enabled. The senders will receive the automatic answer the moment their e-mails are received and you will not have to a single thing manually. A few instances of using auto-responder messages are sending a confirmation that a payment has been received and also the order is being prepared or that a person is on holiday and won't be available for a specific period. In the first situation the function can be activated for a long time, while in the second one it is non permanent. Even though you work with an e-mail exclusively for personal correspondence, you may use an auto-responder to let the email sender know that the email has been received successfully.