EyeBrowse
   Servlet-based, mailing list archive browser, reading standard UNIX mbox format archives and generating HTML dynamically. [Open Source, Apache]
   http://eyebrowse.tigris.org/

Fundamentals of the JavaMail API
   John Zukowski's tutorial at the Java Developer Connection.
   http://java.sun.com/developer/onlineTraining/JavaMail/

Java Outlook Connector
   Offers library to access Microsoft Outlook application and associated data. [Commercial]
   http://www.moyosoft.com/joc/

JavaMail API
   A package integrated with the Java EE platform offering access to mail services. Documentation, tutorials, community services and examples are provided for the package which may also be used as an add-on to the Java Standard Edition.
   http://java.sun.com/products/javamail/

OVP: A Simple SMTP Framework for Java
   Examination of the implementation of a Simple Mail Transfer Protocol (SMTP) client-side framework that can be used in Java applications and applets. Published in Crossroads, the ACM student magazine.
   http://www.acm.org/crossroads/xrds4-4/ovp.html