Disclaimer: I just realized this question may read a little bit as if I'm trying to promote this site. I'm not. Now that I think about it, I'm unsure whether this site even has a proper license from content owners. I'm not in any way affiliated with the site in question.
I just bought a music album from http://www.soundike.com/.
When I created an account, I noticed that they said I would get two free songs simply by confirming my e-mail address. It was true, I clicked a link sent to my Gmail account, and I was then able to download two songs even before paying anything.
Out of curiosity, I then attempted to create a second account using my iCloud e-mail address. The only data the site asks for is my e-mail address and a password. I changed my passwords each time.
I did not receive any confirmation e-mail. (I also checked my spam folder.)
I figured they must be using cookies or my IP or something to prevent multiple accounts. So I activated a VPN and opened an Incognito window in Chrome. I then registered again, this time with an Outlook.com address. No registration e-mail came.
Puzzled by this, I launched Tor and tried to register again with a new Gmail address. No confirmation e-mail, even when accessing the site through Tor.
How could they achieve this? Could they be blocking connections that come from a VPN or Tor?