Classify the open source software, there is a well-known JUnit, JBoss, and Spring.
This time, I am interested in being an open source software introducing Java Email's implementation. At present, my Java project involves Email's reception and sending, I can refer to his architecture and implementation details. Based on the progress of the current project, the difficulty of Java Mail is to be encoded, and others are easier to implement.
http://java-source.net/