Update on Firefox support for OS X
Mozilla will end support for Firefox on OS X 10.6, 10.7, and 10.8 in August 2016. At that time, Firefox will continue to function on these platforms but will no longer receive new feature or security updates.
Firefox Extended Support Release (ESR) 45 will continue to support OS X 10.6, 10.7, and 10.8 until mid-2017, but this ESR release will be the last that supports them.
All three of these versions are no longer supported by Apple. Mozilla strongly encourages our users to upgrade to a version of OS X currently supported by Apple. Unsupported operating systems receive no security updates, have known exploits, and are dangerous for you to use.
As noted earlier/above, Firefox 45.8.0 ESR is the last version supported by Mozilla for Mac OS X versions below 10.9.
As of now, too, the same holds for Thunderbird 45.8.0 (just supplanted by Thunderbird 52, which could well bugger up the Thunderbird email client if one tries to install it).
