Thunderbird team has been developing K9 for years now. This step is a small iteration from a technical point, but significant in that they feel it is stable and complete enough to put their name on.
Thunderbird is technically part of Mozilla but as far as I can tell, they are funded and operate pretty much independently from the browser and other parts of the org.
I definitely support the right of women to uncover their hair in public without getting murdered. Yet you seem to be spending an awful lot of energy defending the regime in Iran.