mailbox synchronizer
Fast Bayesian spam filter along lines suggested by Paul Graham
Client daemon to move mail from POP and IMAP to your local computer
C library for sending e-mail (with attachments) from C/C++
Remote anti spam utility
Gross greylisting server
Anti Spam SMTP Gateway
software for email automation (newsletters, transaction mails, etc.)
JavaScript/XML engine for Apache
an easy to use pop3 client library in C
one server framework