I have used Thunderbird off and on since about 2003. I started using it on Windows and then installed it onto my Linux PCs later on. The point is: Thunderbird is near and dear to my heart.
Unfortunately over the past few years Thunderbird’s importance with Mozilla has faltered. Not because of anything negative, rather because Mozilla is trying to refocus their efforts with Firefox. Most recently, the news that Mozilla is finally letting Thunderbird go took a lot of folks by complete surprise. What was once loved by legions of users has now been placed onto the market for others to adopt it.