SpamEnder stops spam from entering your inbox without blocking any good e-mail. SpamEnder integrates into Microsoft Outlook so it is easy to use. SpamEnder will automatically recognize and work with Microsoft Exchange Server or POP mail. The challenge response functionality helps to update your Accept and Blocked lists. All good e-mail goes to your inbox; bad sender or unknown sender e-mail is kept in Pending and Blocked folders for easy access. Simple and effective. Works with Microsoft Outlook only, not Outlook Express.