What is an autoresponder?

An autoresponder sends an immediate reply when a message is received. Common uses include out of office notices, confirmation of receipt, or basic support acknowledgments.

The classic Out of Office message is known everywhere as OOO. When configured incorrectly, autoresponders can create infinite mail loops in which two systems continually reply to each other, generating thousands of messages and overwhelming servers. Autoresponders keep communication flowing even when no human is present. It is the lighthouse sending a steady signal while the keeper is away.