(STEVEN) is an anti-spam system that validates the sender of the email rather than relying on content alone to determine whether a message is spam or not. The program runs on your local machines and automatically replies to all emails it retrieves with a brief (customizable) message, asking the sender to validate the message by replying to it. Since the majority of spammers will not have a valid address, nor will they reply, it can eliminate almost all spam messages, without deleting any important mail. All messages, that have not yet been validated are added to a special queue from where you can review them, manually approve senders or delete them. Additional features include attachment blocking, web interface with statistics, sender blacklist and more.