This is not a problem at all and doesn't deserve to have a thread, there are three ways to solve this issue, you can ignore the promotional email, you can unsubscribe, or you can log in and change the email to the one that you rarely use, we all have disposable emails, it only proves that you are still not cured and a mere mention of gambling site will get you irritated, a person that is cured of gambling will not get agitated or irritated from this issue, based on your post you still hate Stake.com for the many loss you incurred.
I think you are right here but sometimes things doesn't look the same way we always see it. I believe op can always ignore the messages totally but it doesn't make sense for this kind of thing to be happening for a reputable gambling platform. I know that many other sites do the same without minding your consent which is irrational to me.