SpamAssassin is a common and excellent filtering program with the unsolicited email (spam) may be automatically rejected. SpamAssassin is released as free software under the terms of version 2 of the Apache license.
Filtering by SpamAssassin is based on a sort of hand that performs from a good half dozen volunteers and is sometimes used to update.
SpamAssassin can be used at any point of the mail processing chain, that is, it can at the user level, such as a plug- in in the e -mail program or as a direct call to be in the used procmailrc of the user, as well as on mail server level, where in many e -mail providers, it does its job by being involved in the operation of the mail transfer agents.
The program is written in Perl, each email according to certain rules points that show how high SpamAssassin evaluates the spam probability. With an adjustable threshold value is exceeded, the email is marked as spam and may then mail server level directly deleted, for example, annahmeverweigert stored in special spam folder or spam files, or simply be provided with only one warning Subject; also at the user level can marked as spam e- mail automatically with the aid of filter settings in the mail program in a spam folder, or in a spam folder ( " caughtspam " ) are stored with the learning of the Bayesian filter are supplied.
SpamAssassin uses a variety of mechanisms to distinguish between desirable and undesirable mail ( ham and spam) can be distinguished:
- Static rules based on regular expressions and looking in the mail for sequences, as typically found in spam.
- Querying blacklists of spamming servers, the Realtime Blackhole Lists ( RBLs ).
- Query checksum -based filters such as Vipul 's Razor, Pyzor and DCC.
- Integrated Bayesian filter that statistically the probability calculated based on the classification of previously received messages, whether it is wanted or unwanted mail in new mail.
Means the test text GTUBE can be an installation of SpamAssassin monitoring for correct operation.
Since August 2004 SpamAssassin is a project of the Apache Software Foundation and is licensed under the Apache license. SpamAssassin is thus free software.