The JMatter mailing lists are hosted at Google groups.
Users Mailing List
This list is the main forum for discussions relating to the jMatter framework.
Here is the web address for the mailing list:
Fairly low traffic, with an average of perhaps two or three messages per day.
Developers Mailing List
This list is for discussions related to the further development of the framework. Low traffic mailing list. Perhaps one or two messages per week.
Issue Manager + Wiki