SPAMfighter is an anti-spam software that integrates with email clients such as Outlook, Thunderbird, and Windows Live Mail. The software uses a community-based approach to identify and block spam emails, with over 8 million users contributing to the database. SPAMfighter also includes a whitelist and blacklist feature, as well as a language filter to block emails written in specific languages. The software is easy to use and customizable, allowing users to adjust settings to fit their specific needs.