EyeBrowse
Servlet-based, mailing list archive browser, reading standard UNIX mbox format archives and generating HTML dynamically. [Open Source, Apache]
url: eyebrowse.tigris.org/
Fundamentals of the JavaMail API
John Zukowski's tutorial at the Java Developer Connection.
url: developer.java.sun.com/developer/onlineTraining/Ja...
IBM POP3 Beans
Beans for receiving and decoding POP3 email, and for the user interface of a mail application. [Open Source, IBM Public License]
url: www.alphaworks.ibm.com/ab.nsf/bean/POP3
IBM SMTP Beans
Beans for sending email using the standard SMTP protocol. [Open Source, IBM Public License]
url: www.alphaworks.ibm.com/ab.nsf/bean/SMTP
Plasma
Tries to define a framework for mail applications that makes integrating, replacing and modifying of individual modules as easy as possible. [Open Source, LGPL]
url: www.dfki.de/~beders/plasma/