How it's funded: OpenOutreach is free and open-source, funded by affiliate links and by a promotion for OpenOutreach itself: it ships with a freemium campaign that takes its turn in the sending rotation, sent from your own mailbox under your identity to recipients unrelated to your leads. On an install you run yourself it's opt-out (edit the source), and it has been part of the project from the start. Full detail in the Legal Notice (§4).
Legal disclaimer: Use at your own risk — no liability assumed.