I'd be confused wondering who made the mistake

Confused and Anxious, but a little bit hopeful.

what million? no idea what you are talking about, and even if I did, I would return it swiftly - certainly wouldn't think of first parking it somewhere to make a quick 5-10 percent for myself

If I didn't know why I had one million in my account, chances would be it was an error and the money wouldn't legally be mine, and sooner or later the bank would catch the error. So I wouldn't be relieved, but I wouldn't be scared either. Even if some stranger sent me one million I wouldn't be scared. Maybe relieved? Maybe relieved and a little scared? I wouldn't be scared without being relieved too, though, because the only way I wouldn't be relieved is if I told the authorities and they took it away or something, and then I wouldn't be scared either.

Scared, likely.

That would scare the crap out of me. Advanced payment almost always is for ugly work.

Either. I would go: WHAAAAAAAAAAAA????????????

New phone who dis?

I would be happy and intrigued, relieve comes later when I made sure it's not going anywhere.