Jnestor is a majordomo developed in java: it can reads an IMAP/POP3 folder (email folder), identifies the elements in it and process them, transforming them as Mantis issues.
The software is still experimental, but it passed succesfully the last stages of testing and I hope I will release a stable version soon.
Complete mail business rules processor and MTA. Also provides antivirus (ClamAV) and anti spam (Spamassassin) solutions. Based in Java and OSGI with Spring DM and MySQL data base for statistics. Can be easily extended.
icarusWebMail is an open source WebMail, with POP3 and IMAP mailbox support, also supports APOP POP3/SSL POP3/TLS IMAP/SSL contacts lists from LDAP, anti-spam integration, Internationalization (by now es, en, fr), Filters, Drafts, Sent-Folder, Signature.
Gateway Software that listens to an IMAP folder and
dispatches inbound messages to selected Services.
The default implementation contains a Service to publish
WML and HTML to a web-site via FTP (blogging).
flap is a mail user agent written in pure Java. Its main distinctive feature is mounting message folders (like POP3 or IMAP) into a virtual folder tree, just like on Unix. Other features: macros language (w/ BeanShell) and extensive filter rules.
JaMaRe (JaMaRe ain't a Mail Reader) has grown out of my own need for a hacker's mail filter. JaMaRe has it's own internal mail folder system, and a very extensible filtering system. JaMaRe can also be used as Mail Router.