This project is a fork of MailArchiva Open Source Edition hosted on sourceforge.net, the URL of which is shown below: http://sourceforge.net/projects/openmailarchiva/
Two reasons. The one reason is they seem to have stopped updating the Open Source Edition. The other is the Enterprise Edition has many advanced features, which is great, but I just need a few of them. So why not implement them by myself?
Most developer folks around me use Github but not sf.
GPL v3
Below is from the license of the original version:
MailArchiva Open Source Edition is licensed under the terms of the GNU Public License (GPL) as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.