Free spam filter software for linux

Quick Spam Filter (QSF) is an Open Source email classification filter. Quick Spam Filter is designed to be small, fast, and accurate, which works to classify incoming email as either spam or non-spam.

To recognise spam, QSF strips the text out of the email (using MIME decoding and HTML stripping) and then splits it into tokens (words, word pairs, URLs, and so on). These tokens are then looked up in a database and analysed using the Bayesian technique to see whether the email should be classified as spam or not.

The database is generated by a process of training - QSF is given two mailboxes, one containing known spam, and the other containing known non-spam, to train itself on. After training, if QSF misfiles any email, the message it got wrong can be fed back into the database, thus making QSF learn from its mistakes.

For a more in-depth look at the way in which QSF tokenises and classifies messages, please see the Technical Details section of the manual.

QSF is designed to be run by an MDA, such as procmail.

Sax Filter is a modular set of filters that can be used to process XML documents via Javas SAX support.

Currently, the filters only process content (the ContentHandler interface).

Spam Trainer project makes it easier for GNOME users to train spam filtering software (e.g. SpamBayes or SpamAssassin) that "learns" how to tell the difference between real email (ham) and unsolicited messages (spam).

Not all email clients have spam filtering (and training) built in, and training external filtering programs can be fiddly.

Spam Trainer was written to provide easy (drag and drop) training from the Evolution mail client, and should work just as well with any email client that supports the drag and drop protocol implemented by the GTK+ toolkit.

SSpamM comes from Semis Spam Milter is a spam filter for Sendmail that utilizes spambayes, heurestic spam filtering, and virus scanning (BitDefender, not included).

squid-filter project was designed to build filtering capabilities comparable to those of Muffin into Squid. It consists of
a patch to Squid, containing a module loader and filtering hooks, and a set of filter modules.
Currently available filters:
- Redirection of URIs.
- Rejection of certain (configurable) MIME content types.
- Suppression of cookies.
- Removal of Javascript and ActiveX.
- Breaking of GIF animation loops.
- Detection of 1x1 images.
Main features:
- Modular, easily extensible by writing new filters.
- Flexible configuration. Filters are independent from each other.
- Each filter can take a list of URIs which should not be filtered (allow list). URIs are specified as full regular expressions.
- Client can choose to bypass filters case-by-case.
- Filtering keeps Content-Length where possible.
Purpose
A filtering proxy allows users to remove unwanted stuff from Web pages as they browse them. What "unwanted stuff" is obviously depends on the individual user, but things which are commonly regarded as annoyances include
banner ads, user behaviour tracking via cookies,
animated pictures, JavaScript, VBScript, ActiveX (dangerous as well as annoying).
Some of those things can be avoided by filtering URIs, which Squid can already do via an external redirect program. Others require a content filter.
Usually, a filtering proxy runs standalone and does nothing but filtering. Users have to configure this proxy in their browsers, and if they use a caching proxy too, chain them after the filter. In situations where the user runs Squid anyway (mostly because of caching for different browsers or a small LAN), it is convenient to build this capability into Squid.

ip-filter-cgi is a set of perl script to modify rules of IP Filter (IP Filter is a TCP/IP packet filter cf: http://coombs.anu.edu.au/~avalon/ip-filter.html). If you make any improvement, correction send it back to. The scripts is not complete and is provided for testing purpose.
adulau@metatix.com .
Main features:
- Perl 5.0 (+CGI.pm)
- a HTTP server (Apache)

bilateral filter is a denoising filter using the same technique as the selective gaussian blur, but with speedups and other enhancements.

The filter is slow when the blur radius is small but speeds up when the radius gets larger, which is the opposite behavior of the selective gaussian blur. Theres also an option for improved denoising of image gradients.

Spammer is an anti-spam mail filter for the popular MTA Sendmail.

Spammer checks all IP-Addresses found in the mail header against a DNS blacklist (such as the one from Easynet, Spamcop or Osirusoft).

Depending on the configuration, Spammer rejects mails from well-known spam sources or tags them with an additional line in the header and a special prefix in the subject.

Spammer requires Sendmail to be compiled with milter support. If youre using Debian Linux you need to install the libmilter-package.