makumba has several mailing-lists, hosted at SourceForge
If you need help, have questions, comments, etc., subscribe to the users mailing-list
If you'd like to get in touch with the developers, feel free to contact them.
If you want to take part in makumba development, you can request to be added to the developers mailing-list (if you do so, please send us a mail beforehand so we know you're not a spam-bot :-) )
If you're interested in helping out with building the makumba community, you can subscribe to the community building mailing-list