Fortunately Thunderbird is still available if that works for you. 
Well … sorrreeee … you’re going to lose customers at a great rate with “constructive” comments like that. A couple of us here have spent a fair bit of time actually trying to help you. You could at least take that in the spirit with which it was given. Putting a “smiley” on the end of it doesn’t make it any less unfriendly.
My customer base is just fine, thank you. I am not an employee of eM Client Inc.