As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements handled by Mozilla.
Thunderbird is a free, open-source, cross-platform e-mail and news client developed by the Mozilla Foundation. The project strategy is modeled after Mozilla Firefox, a project aimed at creating a Web browser.
- Various security fixes
- Prepare to use SHA-256 signing certificate for Windows builds, to meet new signing requirement
- In the address book manager, make the contacts sidebar remember the last selected address book
- OS X 10.6 or later