Mozilla has been supporting Thunderbird as a community project for a number of years now. The Thunderbird council which is driving new development has had a couple of major releases and the future, wile rocky looks good. In the medium to long term the Thunderbird council will have to employ people and that will require money. But at this point the fund raising method has not been ironed out. There is talk of donations, subscriptions and partners. What will appear in the end is I hope something free and open. Some recent discussions here https://groups.google.com/forum/#!topic/tb-planning/bigvCJtidHE THe Thunderbird planning mailing list is archived here https://groups.google.com/forum/#!forum/tb-planning the volumes are low and whilst discussion can wander into Technicalities it is the main "notification" pathway as well. Have a read of some of the recent discussions, particularly those initiated by the Council chair Kent James to know exactly what is going on. Without the rumors..