Purgy Short Description:
Anti-spam software for Windows based on a wholly different concept.
Purgy Long Description:
Anti-spam software for Windows. It accepts emails from senders you trust while asking unknown senders to verify themselves by replying to an email. After positive verification it adds them to your approved sender list and delivers all their messages to your inbox.
Integrates with any email program (automatic integration for Outlook Express) and works transparently in the background. Very simple to use.