According to online.casinocity they are owned by I-Services N.V. sites. They have 9 sites: 3 RTG Casinos, 2 TopGame and and 4 other. All licensed in Curacao, but I never heard about any of their casinos.
I recieved same email few days. I'm not going to send my documents, so I put the brand off my site. Not going to work with them. There are many others to work with :)