A webmail-client (POP3, IMAP, SMTP) written in Java as a webapp. Very easy to install - just throw the WAR-file into the deployment-directory of your Servlet-container (tomcat, jetty, weblogic, ..) and you're ready! Test ride on the yawebmail-Homepage!
PIWI is a java based system for managing subscribers and mailinglists and sending newsletters. It runs as webapplication (war) or as standalone application for your desktop, with embedded database (hsql) and webserver. You can use it also per commandline
An Experimental Platform for Secure Peer Services, QARE uses a decentralized trust model, a Public Key Infrastructure and provides single logon for multiple applications running across multiple systems. WAR files are used to add applications.