Hupa is the name of Apache-James' webmail. The name has been selected in respect to the American tribe, and it means in its native language 'the tribe on both ways'.
Right now, Hupa supports IMAP message sources and it performances well, but it is thought to support any James-server storage system in order to improve speed and produce an out-of-the-box package which includes james email server and the webmail.
There is not any official version yet, but the svn code is quite usable. If you want to play with Hupa, you can get the code from svn and package the application with maven. Take a look to the README.txt file in the root folder in order to know how to configure it to use your own server. By default it comes configured to use gmail imap enabled accounts.