What is SpamAssassin?

Spam{{`Assassin is a mail filter to identify spam. It is an intelligent email filter which uses a diverse range of tests to identify unsolicited bulk email, more commonly known as Spam. These tests are applied to email headers and content to classify email using advanced statistical methods. In addition, Spam}}`Assassin has a modular architecture that allows other technologies to be quickly wielded against spam and is designed for easy integration into virtually any email system.

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Spam{{`Assassin's practical multi-technique approach, modularity, and extensibility continue to give it an advantage over other anti-spam systems. Due to these advantages, Spam}}Assassin is widely used in all aspects of email management. You can readily find SpamAssassin in use in both email clients and servers, on many different operating systems, filtering incoming as well as outgoing email, and implementing a very broad range of policy actions. These installations include service providers, businesses, not-for-profit and educational organizations, and end-user systems. Spam`Assassin also forms the basis for numerous commercial anti-spam products available on the market today.

How it works

This flexible and powerful set of Perl programs, unlike older spam filtering approaches, uses the combined score from multiple types of checks to determine if a given message is spam.

Its primary features are:

  • Header tests
  • Body phrase tests. For more information, see SpamAssassinRules.
  • Bayesian filtering (BayesFaq)
  • Automatic address whitelist/blacklist (AutoWhitelist)
  • Automatic sender reputation system (TxRep)
  • Manual address whitelist/blacklist (ManualWhitelist)
  • Collaborative spam identification databases (DCC, Pyzor, Razor2); See UsingNetworkTests.
  • DNS Blocklists, also known as "RBLs" or "Realtime Blackhole Lists". See DnsBlocklists
  • Character sets and locales

Even though any one of these tests might, by themselves, mis-identify a Ham or Spam, their combined score is terribly difficult to fool.

About the Apache Software Foundation

SpamAssassin is an Apache Software Foundation project and is released under the Apache License. The Apache Software Foundation provides organizational, legal, and financial support for a broad range of open source software projects. As a US 501(c)(3) public charity, the Foundation provides an established framework for contributions of both intellectual property and funding for the support of open source software development. Through a collaborative and meritocratic development process, Apache projects deliver enterprise-grade, freely available software products for the public benefit, attracting large communities of users and enabling future innovation, both commercial and individual, through its pragmatic Apache License.