The webmail has been abandoned for a long while.
You could still access your mail via POP:
https://support.chess.com/customer/portal/articles/1444801-how-do-i-get-my-pop-mail-settings-and-setup-my-account-
However, you need to be premium member for that.
I havent been using chess.com for years, but now i need to login to my chess.com email, very important please help how do i login i cant find it please help!!