Free mail filter software for linux

Constrictor is a Python module for parsing, filtering, and delivering mail as a Mail Delivery Agent (like Procmail). Constrictor provides the functionality to easily write a MDA in Python rather than reading some configuration file of its own syntax.
This has the advantages that configurations are readable and self-explanatory (at least, to anyone who knows Python) and that users have the full flexibility of the Python language at their disposal. Constrictor has the ability to deliver to maildir and Unix mbox format mailboxes, as well as bounce, forward, or reject messages.
Constrictor is currently beta software, at best. Im always very leery of software that messes with my mail, since one runs the risk of not only losing messages but, potentially, bouncing mail to great embarassment and chagrin. That said, I am currently using Constrictor on my own mailbox full-time, but, as always, your mileage may vary.
Installation
Constrictor is a single Python module that should be placed either in the directory you intend to invoke your MDA from, or in your Python library directory. The only non-standard module it relies on is the spamd module from the SpamAssassin distribution (available at http://spamassassin.apache.org/full/2.6x/dist/contrib/spamd.py), and only then if you intend to use the "spamassassin()" function to filter your mail (the module is loaded only when that function is called). Constrictor should work on all versions of Python greater than 2.3; it has been tested primarily on 2.3.4, 2.3.5, 2.4.1.
The spamassassin() function connects to a (optionally specified) spamd server (it defaults to localhost). If you do not have a spamd server, you cannot use this function.
For Postfix and Sendmail, edit your ~/.forward to include "|/path/to/filter.py". For more information on invoking this script as an MDA,see your MTAs manual or ask your administrator.
Enhancements:
- This release adds locking code to duplicate database (pickle file used to recognize duplicate messages) access.
- This release contains no known stability or delivery reliability issues, and thus is considered stable.

IMAPFilter is a mail filtering utility. It connects to remote mail servers using the Internet Message Access Protocol (IMAP), sends searching queries to the server and processes mailboxes based on the results.
IMAPFilter can be used to delete, copy, flag, move, etc. messages residing in mailboxes at the same or different mail servers. The 4rev1 and 4 versions of the IMAP protocol are supported.
IMAPFilter uses the Lua programming language as a configuration and extension language.
Main features:
- Definition of filters using many searching criteria available in the IMAP protocol, such as:
- Matching of a string in the headers or the body of a message.
- Size of a message.
- Date of a message.
- Status (recent, unread, etc.) of a message.
- Ability to use logical operators (and/or/not) while defining filters.
- Different actions when a filter matches a message, including:
- Deleting of a message.
- Moving of a message to a mailbox in the same of different servers
- Copying of a message to a mailbox in the same or different servers.
- Changing of a messages flags.
- Listing of the available and/or subscribed mailboxes, along with support for the IMAP CHILDREN extension.
- Internationalisation (I18N) support.
- Server namespace support using the IMAP NAMESPACE extension.
- Secure Socket Layer (SSL) or Transport Layer Security (TLS) encrypted imaps (port 993) connections.
- Encrypted connections using the IMAP STARTTLS extension.
- User authentication with the Challenge-Response Authentication Mechanism (CRAM), specifically CRAM-MD5.

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.

TclMilter is a package for Tcl (written in C) that implements an interface to SendMails Milter (Mail Filter) API for developing custom scripted message rewriting and spam filtering processes.
A thread-enabled Tcl build is required due to Milters threading requirements. However, you can only run, configure, or register callbacks for a milter from the first thread/interpreter the package is loaded into.
If you need to be able to stop the milter from within Tcl, you can load the package in another thread to do so. Only the "milter stop" command will function in secondary threads.
This extension is provided under the GNU General Public License (GPL) (see the file "license.terms" for details).
Main features:
- The smfi_opensocket command is not provided, only milter main as an interface to smfi_main.
- The smfi_setconn, smfi_settimeout, smfi_setbacklog and smfi_setdbg commands, as well as settings normally provided through smfi_main are instead provided as milter configure options.
- The smfi_register command is provided as milter register; however, unlike libmilter its possible to register and unregister callbacks at any time, rather than just once prior to calling main.
- There isnt a single data storage value for smfi_setpriv; rather, TclMilters milter setpriv command uses a hash table so you can set individual, custom variables with data to associate with a context.
- The context provided to callbacks is not simply a pointer, but is an actual Tcl command that can be used to interact with the context.

Mail::Toaster is an installer for a collection of software which provides a full-featured mail server. The system is built around the qmail mail transport agent, with many additions and modifications
Main features:
- SMTP Mail Server (SMTP-AUTH, chk-user, SPF, TLS, tarpitting, RBL)
- Virtual Domain Hosting w/delegated administration
- Virtual Domain Users
- Mailing List (Ezmlm)
- AutoResponder
- Web Based E-Mail (Sqwebmail, Squirrelmail, V-Webmail)
- Web Based Domain Administration
- Mail Filtering (rbls, SpamAssassin, simscan, Qmail-Scanner)
- Virus Scanning (ClamAV, F-Prot, Uvscan)
- SMTP roaming via SMTP-AUTH, POP-AUTH, & IMAP-AUTH
- SMTP roaming via SMTP-submission (port 587)
- POP3, POP3-SSL
- IMAP, IMAP-SSL (Courier IMAP)
- CGI frontend to mail features
- Log processing and pretty graphs (via RRDutil)
- Auto-Installs of MySQL, Apache, phpMyAdmin, and more
- Centralized configuration files
- Support for clusters of qmail servers
- Builds SSL certs for Apache, Qmail, & Courier
Security - Mail::Toaster supports secure connections from the email client (via POP3, IMAP, SMTP, and webmail) to the server. If the remote (destination) email server supports it, we also encrypt the email as it travels across the public Intenet from server to server. Thus, if you happen to be using two Mail::Toasters and your email clients are configured to use SSL, you have a fully encrypted path from the email sender to the final recipient.
State of the Art Filtering - Mail::Toaster has sophisticated filtering capabilities built right in. A default installation blocks all viruses and will detect 85% of the spam. With a little bit of training, its reasonable to expect and achieve 99% spam filtering accuracy.
Flexibility - Mail::Toaster provides an extremely flexible framework to allow you to build your email system your way. This flexibility makes it easy to migrate existing systems to Mail::Toaster and also allows Mail::Toaster to work in diverse environments and OS platforms.
Support - There is a thriving and active support community available on the mailing list. The web forums are also frequented by quite a few helpful folks. If you need more support than folks are willing to provide, commercial support is available.
Enhancements:
- Primarily code quality improvements.
- Rewrites of major portions of the code using techniques described in Perl Best Practices.
- Many more tests, much better tests, and more error testing within the functions.
- A new Webmail interface.
- Its not terribly "pretty" yet, but is much more user friendly and functional.

spfmilter provides a Sender Policy Framework (SPF) milter for Sendmail.
spfmilter is a milter (sendmail mail filter) which implements the Sender Policy Framework (SPF). SPF is a strategy for preventing junk mail. The SMTP standard for email allows anyone to forge anyone elses email address.
SPF verifies that the Sender address of an email message matches (according to some policy) the client IP address that submitted it.
The idea of SPF is to prevent email forgery. Each participating site sets up a little definition of which hosts are allowed to send mail claiming to be from that site. When another site receives mail, it checks the permitted-senders definition for the originating site. If the check fails, the mail is rejected.
Setting up the permitted-senders definition is very easy, you go to the SPF Wizard and fill out a little form, then put the resulting string into your DNS records. This milter implements the second half of SPF, checking the mail you receive against other sites SPF records.
Enhancements:
- Some improvements to the redhat rcscripts. (Paul Howarth)
- Deal with the unknown-family connections which occasionally show up on some OSs, such as Solaris. (Joel Lord)

FIR filter Plugin is an effect plugin for XMMS which enables to filter audio data using long FIR (finite impulse response) filters. Typical applications is loudspeaker or room equalization which typically requires filters with more than 300 taps (filter weights).

The FIR filter plugin uses the fftw3 library to perform the filtering using the overlap-and-add method. If fftw3 is not available the plugin will perform the filtering (convolution) in the time-domain which is much less efficient for long filters.

morigin email classifier is a filter that classifies and tags email messages based on the DNS information of the system submitting the mail to your organization.

morigin email classifier can then be used to improve upon existing spam filters such as SpamAssassin.