Apple Mail on OSX 10.4 (originally NeXT) working well today fyi
the industrial strength, bullet proof, complex but profoundly reliable engineering within Apple Mail shows itself to have stability over decades.
Why is this Thunderbird rewrite going to succeed ? A glossy sales pitch makes it less convincing, not more. This is a years' long project with no guranteed outcomes.. in fact, I would suspect that noveau security trappings and trend-based GUI embellishments would almost guarantee a "mayfly life" at great expense, contrasted to the Oak trees of original Internet standards.
cynical? perhaps.. prove it wrong