John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types commonly found on Unix systems, as well as Windows LM hashes. On top of this, lots of other hashes and ciphers are added in the community-enhanced version (-jumbo), and some are added in John the Ripper Pro.
whatsnewfm is a filter for the daily freshmeat newsletter. It shows only news items that you haven't seen before (so you don't have to read about every update of applications that you aren't interested in). You can also set up a list of "interesting" applications where you want to be informed of every update.
SAGATOR is an email antivirus/antispam gateway. It is an interface to any smtpd that runs an antivirus and/or spam checker. Its modular architecture can use any combination of antivirus/spam checkers according to configuration. It currently supports ClamAV, nod32d, AVG, Sophos, TrendMicro AV, Symantec AV, Spamassassin, bogofilter, and quickspamfilter. It has some internal checkers (string_scanner and regexp_scanner). It can parse MIME mail and decompress archives.
The AmavisNewSQL SquirrelMail plugin gives you per-user control of a subset of SpamAssassin settings which are stored in a database. It also allows you to use a quarantine database for questionable mail. This plugin was designed with enterprise use in mind, and differs from other plugins in that it works with amavis-new rather than SpamAssassin directly. Most of the code lives in an external class that you can reuse in your own admin tools. It even has support for SOAP calls to perform common tasks.
maildirproc is a program that processes one or several existing mail boxes in the maildir format. It is primarily focused on mail sorting, which means moving, copying, forwarding, and deleting mail according to a set of rules. It can be seen as an alternative to procmail, but instead of being a delivery agent (which wants to be part of the delivery chain), maildirproc only processes mail which has already been delivered. That is a feature, not a bug.
DynaStop is a utility to examine IPv4 based addresses for Exim and procmail for the purpose of filtering based upon patterns defined by the administrator. This can be a pivotal factor in email filtering and server load management, since dynamic IP addresses are typically used for dial-up, DHCP, and DSL accounts. All of which have a designated mail exchange server through which all outbound mail flows as defined with many, if not most, large Internet service providers.
mxallowd is a daemon for Linux Netfilter (using libnetfilter-queue) and BSD pf (using pflog) which implements a slightly improved nolisting mechanism. It requires your name server to be configured to return two MX IP addresses, and the one with higher priority must not run a mail server on port 25. mxallowd blocks attempts to connect to the mail server unless the sender tries to connect to the first mail server before the second. Since most spammers will attempt direct connections to each mail server, they will be blocked.
dyn-host-filter is a stand-alone application used to restrict the access to qmail based on the client's hostname/IP. Each incoming entry is compared to a user-defined list of regular expressions. dyn-host-filter may reject a matching entry by modifying the RBLSMTPD env. variable used by tcpserver.