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.
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.
vmm is an easy-to-use and configurable commandline tool for administrators and postmasters, used to manage domains, alias-domains, accounts, and relocated mail users. It allows fast and easy management of mail servers. It's designed for installations using Dovecot and Postfix with a PostgreSQL backend.
mailprocd is a standalone mail classification and delivery daemon for massive multiuser servers, designed to extend the capabilities of MTAs such as Postfix and sendmail. It embeds perl in C in order to use SpamAssassin efficiently. It implements a process manager with persistent spam checker processes running under users' own UIDs.
Greylite is a SPAM filter with exceptional effectiveness and without false positives. It combines natively with qmail and works as a proxy for any SMTP server. It implements a modified greylisting algorithm that improves the filtering effectiveness and minimizes the delay drawbacks associated with the standard greylisting algorithm. It is self-contained because it uses SQLite, and is easy to setup and maintain, small, and fast.