DSPAM

DSPAM is a free software statistical spam filter written by Jonathan A. Zdziarski, author of the book Ending Spam () and other books. It is intended to be a scalable, content-based spam filter for large multi-user systems. DSPAM is distributed under the terms of the GNU General Public License.

The project consists of a library, libdspam, which contains the core filtering and storage routines, and command-line and web-based interfaces. DSPAM is MTA-independent, can store spam classification data in a number of database formats, and uses bayesian filtering, among other techniques, to learn and adapt to spam.

DSPAM's original author claims that some users of DSPAM have reported as high as 99.5 to 99.95% accuracy, including “best recorded levels of accuracy ... 99.991 % by one avid user (2 errors in 22,786) and 99.987 % by the author.” However, at the spam filter test performed at TREC 2005 the best-performing DSPAM configuration had misclassification rates worse than other filters in the test and below stated levels of accuracy. Zdziarski protests these results.

The rights to the project were sold to Sensory Networks in May 2007. Development of DSPAM resumed in December 2007, with Sensory Networks publishing 27 community-created patches to the CVS tree, along with a new PHP-based WebUI in development. A fork of dspam, dspam-community, was registered at SourceForge on October 10, 2008.

On January 7, 2009, Mick Johnson of Sensory Networks announced that they are “looking at shutting down the hosting for the Dspam server by the end of January.” On January 12, 2009, Mick sent a follow-up email, stating that “We are handing over the trademarks, copyright to the Dspam source, the Dspam website, and administration of these mailing lists” to “the crew at dspam-community.”

DSPAM and dspam-community merged in January 2009 and the development of the project continued under the name DSPAM, driven by a community of developers and users. As of 2014, DSPAM has no active developers.