When going away on holidays, you will find this option useful. AutoResponder will send an automatic message back to any sender, who sends you a new message with a notification of your choice.

Another popular use for this feature is to let the sender know that the message has been received and they will be contacted shortly.

Log in to The Console™
Click on the icon called "Webmail"
Click on an existing e-mail address (there is no difference if it is a POP/Alias/Catchall)
In the section "Auto Responder" enter the subject and the body of the message.
Click "Create".

You can test this immediately. Send a message to the address you just edited and you should receive an automatic response back with the message you entered in The Console.