Originally Posted by k0nr4d

Right, and to collect on it they'd have to sue you in Australia because a USA judgement doesn't mean anything in AU. They won, but really if you aren't planning on having any assets in the US it doesn't matter much.

My advice to OP is to ignore everything they send you. If you confirmed receipt of it or not, It's not a certified letter and you don't really know who is emailing you or why. It might be someone phishing for your data to do some identify theft or do use this data after to do bank account changes on affiliate programs you work with. You have many, many reasons to believe that it could be a scam.

The police doesn't work like that. If they needed to contact you, they would subpoena your domain registrar or host for your information and send you a letter.