Amber sits in the tcpserver chain for qmail and implements an "amber list" for incoming mail. This neither accepts nor rejects connections, but implements a number of timing-related tricks to fake out spam and virus software that doesn't implement SMTP correctly. For example, it can defer requests from new IP addresses for a few minutes before it starts passing connections on to smtpd, pause and check for programs that send data before the HELO, and otherwise make things rough for bandit bulk mailers.
Wumi is a sendmail milter using the py-milter. It rejects mail containing certain (configurable) attachment filenames (.exe, .pif, etc.) or containing a virus (checked by calling a single-user license command line scanner) by answering the SMTP DATA step with "554 5.7.1". This way, the mail server does not have to generate senseless bounces.
blists is a Web interface to mailing list archives. It works off indexed mbox files. It includes two programs: bindex and bit. bindex generates or updates the index file (incremental updates are supported). bit is a CGI/SSI program that generates Web pages on the fly. Both programs are written in C and are very fast.
PbulkMailer is a bulk email application. Instead of a database, it works with CSV files and has a simple text file configuration. It sends directly to an MX, via a smarthost/relay, or through email accounts. Plain text and HTML messages are supported along with attachments. Per-email customization of subject, name, and body elements is allowed. Delivery and failure are logged to CSV files, and message reads, unsubscription, and spam reporting are handled using included PHP scripts.
The MIME Email message class composes and sends MIME encoded email messages. It features user-definable headers and body parts, support for plain text and HTML body, headers with non-ASCII text, HTML messages with embedded images, file attachments with content type detection, forwarding of messages as attachments, setting the error delivery address with the Return-Path header, and sub-classes for different delivery methods: mail, SMTP, Qmail, Sendmail, and Microsoft IIS or Exchange pickup folder. It also supports sending personalized bulk mail by replacing the message parts that differ for each recipient.
PHP MIME Mail decoder class is a PHP class to parse and decode MIME email messages. It supports decoding single RFC 2822 MIME messages or archives that aggregate multiple messages in the mbox format. It can decode messages read from files or data strings. The bodies of multipart messages can be decoded into distinct sub-messages. Optionally, the message body data can be saved to separate files, so the class can handle messages larger than the available memory. The parser can tolerate some syntax errors in malformed messages that are not compliant with RFC 2822.