Thunderbird and Firefox are developed by separate companies (both under the Mozilla Foundation). Thunderbird is funded through donations. Firefox is funded through (among other sources, such as Pocket and advertisements) the Google search deal. As far as I know it’s not legally feasible (or even possible) for the Firefox money to go to Thunderbird or vice versa.
Thunderbird and Firefox are developed by separate companies (both under the Mozilla Foundation). Thunderbird is funded through donations. Firefox is funded through (among other sources, such as Pocket and advertisements) the Google search deal. As far as I know it’s not legally feasible (or even possible) for the Firefox money to go to Thunderbird or vice versa.