Gmail alone works well for even though I have multiple emails from my casino account that I created long time ago.
Gmail has the feature of centralized inbox that let you see all the email of your account and merge it on single mail. Just clicking the drop down to check the receiver mail is what I’m doing to determine which is the correct email for the specific casino account.
This is much simpler than using other 3rd party apps that is not accessible anytime for me.
Other email providers which respect much more users privacy can also do that. Such as protonmail.
Proton Mail is a very nice email provider, highly recommened. It also allows such redirects.