spam.pl reads an email from stdin and creates a complaint mail which it sends to the postmaster and abuse-receivers of the domains that have relayed the mail. It is customizable to prevent complaining to friendly hosts, uses your own complaint mail and is ready to be invoked from within another mail program.
Spamfilter is meant to be used via the .qmail files that the qmail mail system uses to control what to do with incoming emails. This program will give you the opportunity to control which mails you want to receive and which are to be thrown away. It does this by checking if the mail is directly addressed or not, and then checking various configuration files to see what to do. The two most important files are .allow and .deny that should reside in your home directory.
Turner will turn your boring old source code (C, C++, or Java) into colorized HTML ready to be displayed on a web page. Along with colorizing the source code, turner will also bolden keywords and italicize comments, convert tabs to spaces and optionally insert assorted usefull bits of HTML stuff (a 'home' link or a 'last modified' entry). While it's not the first of it's kind, nor the most versatile, it is small, fast, and totally self contained.
Vipul's Razor is a distributed, collaborative, spam detection and filtering network that exploits the broadcast characteristic of spam distribution to limit its propagation. The primary focus of the system is to identify and disable an email spam before its injection and processing is complete. Razor establishes a distributed and constantly updating catalogue of spam in propagation. This catalogue is used by clients to filter out known spam.
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.
XCmail is a MIME and multi POP3 capable mailtool for X11 using the Xclasses X11 layout library. Its main purpose is to read and write mail, allowing any kind of data to be attached. It can handle MIME types, has helpers to show different types, and can encode and decode binary data into ASCII to allow it to be transported as mail over the Internet. It has many built-in functions such as 2 vCards, unlimited POP3 servers, SMTP, SMTP after POP3, SMTP-AUTH (RFC2554), addressbook, encoders, filters, a special spam filter, spell checker, xface, and a new "virtual folder" concept. It also uses external programs to enhance its feature set. XCmail can be extended through a plugin interface.
XFMail is an X11 application for receiving electronic mail. It implements most of its email functionality internally so that it does not depend on a lot of extra packages. It supports POP3, MBOX, IMAP4, sendmail, and SMTP. It has built-in support for interfacing with PGP, GPG, ispell/aspell, faces, LDAP, and esound. It runs on most Unix variants.
xlHtml converts an Excel spreadsheet file (.xls) into highly-optimized HTML. It includes scripts to allow it to be used as a Netscape or mutt plugin and as a xls handler for Apache. The program currently supports string, blank, boolean, error, integer, floating point, hyperlinks, and formula cells. It can also output in XML, tab delimited, or comma separated values (CSV).