Consider me sold. But for the love of everything, please update Thunderbird to natively have “start at system startup” , “minimize on startup”, “close to minimize”, and “minimize to tray” features. I know there are extensions for them but they are fickle getting them to play nicely with each other and temperamental depending on which linux distro and desktop you use.
I hope they succeed. While a normal user might not need more than Thunderbird currently provides, organizations are mkre or less bound to solutions like M365 for their versatility.
The only reason I don't use Thunderbird is because I want to minimize it. I do not want to alt-tab cycle through background apps like email or music (looking at you, Rhythmbox). Why is that such a difficult UX thing to understand? And I don't want to install add-ons for that.