DSPAM is a scalable and open-source content-based spam filter designed for multi-user enterprise systems. On a properly configured system, many users experience results between 99.5% - 99.95%, or one error for every 200 to 2000 messages. DSPAM supports ma
qpsmtpd is a flexible smtpd daemon written in Perl. Apart from the core SMTP features, all functionality is implemented in small "extension plugins" using the easy to use object oriented plugin API.
Yet another antispam software package, this one is real time monitoring that can get a 'feel' for emails as they mutate in real time, and allows for collaborative spam identification
The DCC or Distributed Checksum Clearinghouse is an anti-spam content filter. As of mid-2004, it involves millions of users, tens of thousands of clients and more than 250 servers collecting and counting checksums related to more than 150 million mail mes