This step is not necessary to use the standard out of the box version of James. A pre-built binary version of James is available from the James download directory. But if you wish to customize the James source code, it will be necessary for you to build the distribution yourself.
There are two ways to get the James source code.
1. Download the source distribution - the source is available from the James release mirrors. Simply choose the version of James you'd like to download, and pick the source distribution appropriate for your platform.
2. Get the source code using SVN - this method gives you access to the cutting edge code base. Instructions on how to use SVN to get the James source code (the jakarta-james distribution) can be found here. James server repository is here.
To run the build you need two third-party tools.
1. Java Development Kit - You must have a JDK of Java version 1.4 or higher installed to build the James distribution. The exact JDKs available depend on the platform. A JDK must be downloaded and installed before the build can run.
2. Ant - This is a Java-tailored, XML-configured, extensible build or make system. You need ant (1.6+) in order to build James. You can get the latest version of Ant here.
In the top level directory of the source distribution you can use ant, simple set the environment variable JAVA_HOME to the base directory of the JDK. Then run the build with any of the following command line arguments: