Challenge-Response System

Glossary

Challenge-Response System

Glossary

WebDynamic Web Glossary

An anti-spam program that requires a human being on the sender's end to respond to an emailed challenge message before their messages can be delivered to recipients. Senders who answer the challenge successfully are added to an authorization list. Bulk emailers can work with challenge-response if they designate an employee to watch the sending address' mailbox and to reply to each challenge by hand.

Challenge-response systems use a number of different approaches to the task of separating humans from machines. Typically, when a message is received, the system sends a reply that includes a URL linking the user to a Web site. At the Web site, the user is asked to perform some task that, while easy for a human, is beyond the capabilities of an automated spamming program.