This should not only be about gambling sites but also about other platforms like exchanges, banks and everywhere you are online even if it is not about money, you still need to make sure that the emails you are receiving are actually from the platform that you registered with and not from another place. It can be a means to scam if not from the platform you registered with.
This plays very important role in our life always and regularly check the mails sent our inbox needs to be carefully monitored otherwise it would really affects us, and someone could fall trap while trying to respond the mail or even becoming track while gambling. Most times i do wonder where do they usually gets those personal mail because if they don't use to apply for the platform it would never be revealed and this also implies the gambling aren't also secure.