Baruwa (Swahili for letter or mail) is a mailwatch-inspired Web 2.0 MailScanner front-end. It provides an easy to use interface for users to view details of messages processed by MailScanner as well as perform operations such as releasing quarantined messages, spam learning, whitelisting and blacklisting addresses, etc.
DRBImageVerification is a simple anti-spam image verification, or CAPTCHA, script. It allows you to add a challenge-response test to your existing PHP powered forms to prevent automated spam postings. The verification string length and character list are configurable. The script requires a session cookie for additional obscurity. It includes an example PHP page demonstrating how to add a verification image to an existing form.
DSPAM phpControlCenter is an incredibly discerning open-source spam removal utility .
Form Spam Bot Blocker
Form Spam Bot Blocker is a PHP class that can generate forms that prevent submission by spam robots without requiring human users to enter special values.
OpenBottle is a per user anti-spam system based on a sender authenticated whitelist mechanism. The core of the system is written in Perl, with a web driven user interface in PHP.
A PHP-based spam & virus/worm filtering for POP3 email accounts. Designed to run as a cron job and catch spam based on links to blacklisted IPs, obfuscated words or blacklisted phrases; attached-image spam; email worms; corrupted or malformed emails.
ProcBuilder is a basic web interface to creating and editing Procmail recipes. In order to run it on your site some changes will probably be needed.
QSpamDog is a PHP-based email filter which is intended to be used primarily in filtering spam email. It was designed for usage with QMail based email-servers which use the Maildir format for storing users' emails.
gwi is a web-interface to SQLGrey (SQLGrey is a greylister for Postfix). This web-interface enables you to edit the white- and blacklists as well as the current state of the greylist.
The spaminator is a server that is placed infront of your email server that allows you to take full advantage of the anti-virus/spam features while keeping your current email server intact.
Spamity is a Web interface for Postfix log files that makes it possible to view filtered spam messages, which is useful for testing the effectiveness of filtering rules. Authentication is possible through an IMAP server, and desired accounts can receive administrator privileges. An option to reinject quarantined messages is provided.
Sugarplum is an automated spam-poisoner. Its purpose is to feed realistic and enticing, but totally useless data to wandering spam-bots such as EmailSiphon, Cherry Picker, etc.