I only wonder why you provided them your email address which matters. I never do such things and use for casinos one of my numerous "anonymous" emails which I almost never check. ( Rare checks commonly resulted in deletion of all content in all boxes (no matter whether it is a spam one or some others). The letter you have received is certainly the fishing one. I'm sure the most casinos' data bases are already leaked.
If you don't provide mail how then do you signed up or do you use mobile number to get registered? That is if you are saying that it then means that shouldn't had used a regular mail than spare mail to signup right, Okay I know is good having spare mail but still there are some messages that happen to move to spam box which I know those mail aren't useful it could be promotional mail. Op shouldn't take whatever mail into account but I love what he did to have at least share here for people to know whether it's real or not.