MouseTrap will reduce or eliminate junk mail (spam) using a Reply-Authenticate method for senders of e-mail.

MouseTrap integrates between your e-mail program and your mail box. MouseTrap receives the e-mail in your mail box and checks a list of authorized senders. If a sender is not authorized, MouseTrap will reply to the sender, asking the sender to reply to an authorization message. When the sender replies, MouseTrap automatically adds the sender to the authorized sender list.