Autoresponders are emails which are automatically sent in response to a message that has been received. This function is automatically activated by email users who may not be able to respond to emails when they go on vacation or when they step out of the office to make sales calls.

The email which is automatically sent is referred to as an autoresponse.

Autoresponders also work when a buyer purchases something on the Internet. For example, after the purchase of a plane ticket has been completed, an email is automatically sent to the buyer’s email address, confirming the purchase and outlining the flight details. In the future, the buyer can expect to receive more emails from the airline company or travel agency from which the ticket was purchased, this time for information on travel promotions and updates. In this case, autoresponders also serve an advertising function.

These may also be used by companies who provide trial versions for their software. For instance, if a user downloads the trial version of a brand of online conference software, he or she will have to provide an email address. The user may then receive an automatic email or two before the trial version expires, which may give more information about the advantages of purchasing the full version, as well as give tips on how to maximize the use of the service. It is often not enough for this email to be sent once, and reminders may still be sent long after the trial version has expired, until the user finally disables this function.