@shauna add another wrinkle and MZLA (the Mozilla entity that houses Thunderbird) - has a co-governance model between a board and a Council, elected from contributors. This gives the community immense power (we can't approve a yearly budget without the Council's input, for instance). While it has been hard to have so many different stakeholders, I believe it has kept us honest and true to the mission of great open source communication software that champions open standards.