SubEthaSMTP is an easy to understand Java library that provides a receptive SMTP server component. By plugging this component into your Java application, you can easily receive SMTP mail using a simple abstract Java interface. Also included is a small sub-project called Wiser, an easy to use incoming mail testing framework.
p-unit is a framework for unit testing and performance benchmarking. As a unit test, it can run with a single thread or multiple threads against the same test code. p-unit has an executor pool which can accelerate the execution speed dramatically. As a perforamnce test framework, it records memory consumption and execution time, and generates results in the form of plain text, image, and PDF file. Users can also easily register their own reporters by implementing the p-unit event listener.
x4juli is a port of the main parts of log4j to the J2SE Logging API. The default implementation is incomplete and therefore still not widely used, even when introduced in J2SE 1.4. x4juli provides logmanagers, formatters, handlers, and filters to fill the gap. The interface and use of the original API has not been changed. Additionally, x4juli delivers a native implementation of the Jakarta Commons Logging (JCL) API and the Simple Logging Facade for Java (SLF4J) API.