Other Mail Servers in Java

Here's a list of some of the other open source mail servers written in Java:

GreenMail - http://www.icegreen.com/greenmail/: GreenMail is a suite of email servers designed to ease the testing of SMTP, POP3, and IMAP clients. It allows users to easily create servers with specialized behavior other than actually delivering or storing email, so it's ideal for unit testing code that depends on a mail server.
Jakarta James - http://jakarta.apache.org/james/: James is probably the most ambitious of Java mail servers. Since it's a Jakarta project, it's under active development with strong visability. An IMAP implementation is in proposal state, but POP3 and SMTP are stable. James is flexible, particularly due to the great Mailet API.
Java Mail Server - http://www.ericdaugherty.com/java/mailserver/index.html: I don't know anything about it.
JAMS - http://www.kimble.easynet.co.uk/jams/: I don't know anything about it.
Java Mail Server - http://jmailsrv.sourceforge.net/: I don't know anything about it. "Java Mail Server" seems to be a popular name.