The announcement of the first Firefox ESR (Extended Support Release) coming with Firefox 10 on January 31st also means Firefox 3.6 support will finally be ending. Mozilla will end support for Firefox 3.6 on April 24th, 2012 which is 12-weeks after the first Firefox ESR launch on January 31st, 2012. Firefox 3.6 was released in January 2010 and will be the longest running Firefox release at 27 months (followed by Firefox 2.0.0 which was retired after 22 months).

Mozilla has announced Thunderbird will follow the Firefox Extended Support Release (ESR) plan. The current plan is the first Firefox ESR will be based off of the upcoming Firefox 10 release coming at the end of this month. With that release comes a 12-week ‘grace-period’ for continued support of the Firefox 3.6 release which would put the final release on April 24th, 2012. However, Thunderbird has been a bit slower to adapt to new release processes (the first rapid release cycle release was Thunderbird 6). It is uncertain at this time if the first Thunderbird ESR will be based off…