What is an autoresponder?
An autoresponder is a program that automatically responds to incoming email messages. An autoresponder is generally included as a feature in an email program or service, but third-party autoresponder software is also available.
Autoresponders were originally designed to reply to all incoming emails when the recipient was unable to reply, for example while on vacation. The simplest autoresponder can be configured with most email programs and services that allow a recipient to send a prepared message to all or to select incoming email messages.
An autoresponder is also used in email-based subscription processes in which it automatically generates and sends an email for new registrations. It is also used with online programs and services to send a message about specific triggers - for example, to notify subscribers of their email storage quota.