@thunderbird
Great to see you around the Fediverse 
And I'm looking forward to see #Thunderbird on Android
However, I think that @Ahorn and @fuomag9 have raised two important points that I'd like to second:
Please plan to publish your app via #FDroid right from the start - and include encryption via #PGP and #SMIME 
Oh - and just drop the word here when you start looking for beta testers 