AMaViS (A Mail Virus Scanner) scans e-mail attachments for viruses using third-party virus scanners available for UNIX environments. It resides on a UNIX (Linux) machine and looks through the attached files arriving via e-mail, generates reports when a virus is found and sets the delivery on hold.
The Aardvark Shell Utils is a collection of three utilities designed to aid the user when working with shell scripts or from the command line. All three accept input on the command line or from standard input, and thus they can be piped with other commands. All commands come with their own man page. Included are realpath, filebase, and fileext.
AqMail fetches mails from remote mailboxes (POP3), applies admin-defined filters, and stores the email in local mailboxes for POP3 daemons to serve them. It supports virtual mail domains and users. It has been tested with QMail as the MTA and with Spamassassin and ClamAV as filters.
Attachment Ripper and Displacement System (aradis) is a filter that removes attachments from email. The removed attachment is sent to a specified resource for storage. The attachment is replaced with a notice of where the removed attachment may be found. The filter can also rename filenames for security. It uses GMime for MIME handling.
B's Harmaa is Postfix policy server that implements greylisting and sender policy framework. What differentiates it from other similar programs is its unique autowhitelist feature. When a request for delivery of a message is received by Postfix via SMTP, the triplet CLIENT_IP / SENDER / RECIPIENT is built. If it is the first time that this triplet is seen or if the triplet was first seen less than one minute ago, then the message gets rejected with a temporary error. Spammers often will not try again later, even though it is required per RFC.
BLD stands for "blacklist daemon" and is intended to serve a blacklist. The blacklist is built by simply inserting IP addresses or by using submission rate limits based on a maximum number of submissions of the same IP address within a minimum time interval. A BLD cluster can be built by configuring the daemon to notify other similar daemon(s) every time an IP address is added to the blacklist. BLD was primarily designed to fight against dictionary-based spam (by making the MTA report to BLD any host that tries to send email to an unknown user), but can be used by any program.
BarricadeMX provides very accurate, high performance spam and virus protection for Enterprise and ISP sites. Features include simple installation and administration, little if any end user interaction required, no quarrantine required, and an optional custom non-delivery receipt for all rejected messages. It uses a custom version of SpamAssassin along with many proprietary anti-spam techniques to achieve a guaranteed level of over 99% accurate spam detection with fewer than 0.1% false positives.
This is a mail filter which uses the Bayes algorithm as explained in Paul Graham's article "A Plan for Spam". It aims to be smaller, faster, and more versatile than other filters. The implementation is ANSI C and uses POSIX functions. Supported platforms are (in theory) all POSIX systems. It is independent from external programs and libraries, supports multiple database formats (flat files, libdb, and MySQL), and uses efficient zero-copy processing. SpamAssassin style passthru mode and headers are supported.