GLD-fork is a fork of the GLD program by Salim Gasmi. The fork has been made because the original project has been dead for many years, and some new featured were needed. GLD-fork, as with the original GLD, adds greylisting functionality to the Postfix mail server. Greylisting is a fairly resource friendly anti-spam technique. GLD-fork can easily be combined with other (more resource consuming) tools to build anti-spam protection.
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.
OpenFWTK is an application proxy toolkit which inherits the ideology of TIS fwtk and maintains API backwards compatibility. The design goal is to make it simple yet powerful; no performance hacks are allowed in the code and library dependencies are reduced to a minimum. It is a true application layer filter. It features unified pluggable content inspection for the most frequently used protocols, NAC (Network Admission Control), and the ability to define fine-grained Internet access policy based on browser identification.
GNU parallel is a shell tool for executing jobs in parallel locally or using remote computers. A job is typically a single command or a small script that has to be run for each of the lines in the input. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables. If you use xargs today you will find GNU parallel very easy to use, as GNU parallel is written to have the same options as xargs. If you write loops in shell, you will find GNU parallel may be able to replace most of the loops and make them run faster by running several jobs in parallel. GNU parallel makes sure output from the commands is the same output as you would get had you run the commands sequentially. This makes it possible to use output from GNU parallel as input for other programs.
fdm (fetch and deliver mail) is a simple, lightweight replacement for mail fetching, filtering, and delivery programs such as fetchmail and procmail. It can fetch using POP3, POP3S, IMAP, IMAPS, or stdin, and deliver to a pipe, file, maildir, mbox, or SMTP server, based on a set of regexps. It can be used for both single user and multiuser setups, and is designed with privilege separation when running as root.
Sendmail Sender Address Validator is a lightweight, fast, and reliable Sendmail milter that implements a real-time Sender email Address Verification technology. This can stop some kinds of spam with a spoofed sender's email address. It also implements real-time Recipient email Address Verification, which can be useful if your machine is a backup MX for the recipient's domains, or if your machine forwards all email messages as a relay host for your domains to another internal or external email servers. It is a light alternative for the spamilter, milter-sender, and milter-ahead milters.
milter-spamassassin is a lightweight, reliable, and fast Sendmail plug-in for the SpamAssassin mail filter. It uses advanced statistical and heuristic tests to identify SPAM built into spamd (the SpamAssassin daemon program). This filter has a hosts/networks whitelist, scans messages less than a defined size, rejects SPAM messages at the DATA stage of SMTP session, copies SPAM messages into the special "garbage" mailbox, performs Subject tagging if SPAM is detected, and adds an information header to scanned messages.
milter-clamav is a lightweight, reliable, and fast Sendmail plug-in for the ClamAV antivirus scanner. It uses a mail scanning engine built into clamd (the ClamAV daemon program). This filter scans messages less than a defined size, rejects infected messages at the DATA stage of SMTP session, and adds an information header to scanned messages.