Along with Firefox 188.8.131.52, Thunderbird 184.108.40.206 has been released as well. The release notes for Thunderbird are a bit brief:
- Improvements to product stability.
- Several security fixes.
The Mozilla and OSU OpenSource Labs FTP Servers appear to be overload at this time but you should be able to download Thunderbird 220.127.116.11 directly from the product page. Most users should be able to upgrade Thunderbird (if it hasn’t told you to do so already) as well as Firefox by going to the Help menu and selecting ‘Check For Updates…’