Brilliant… Can’t wait to see how far we can get destroying the planet

Does the sun classify as a nuclear reactor? Because they could just use solar power

I found it a bit dodgy when companies use outlook or Gmail instead of their own domains for emailing

I use enpass because you can choose where to store your pass db. Also, proton released their own password manager

No one said that Thunderbird keeps copies of your email. But there are apps that do that and the OP does not want one of them.

No, I am saying that OP is looking for an alternative client, which also doesn’t upload their emails. For example, mailspring would be a bad recommendation because, as far as I know, it uploads your email to their server

They mean mail apps that keep a copy of your emails in their servers