I think you are a bit confused about the E-mail structure.

Everything behind the @ is the domain, on your case “domain.com” Before the @ is just a name that can be used as you, the domain owner, wants.

If you want to redirect all mail to yourname@domain.com, that’s very easy to do AND you can still see the original e-mail address these nails were sent to.

So I assume for example Dropbox sent some commercial mail about current offers. Using that, he knew the old account and that it was signed up to Dropbox

It’s from an Apple commercial, which was an allusion to 1984

Have to? Been playing on Linux for years, haven’t had many issues so far.

I just bike to work.