I had a similar issue with Sony/PSN recently. Someone had registered their account and even though I received a validation email I didn't click the link. I then got a welcome-to email a few days later.

PSN's emails don't have a "This is the wrong email" link like some services do, and the US support page link geo redirects to a UK 404 page. I had to go googling for an email address to complain to in order to remedy this.