Changing your username doesn't affect your @chess.com email address at all. The only thing that will affect it and cause issues is if you change password.
When you change username, from the immediate time we do this for you, you will need to use the new username "but" same password as before.
Everything you've ever posted on, all your games, messages etc will show as your new username, but it doesn't affect the @chess.com emails at all.
If for example you add a 1 to your username, but your @chess.com doesn't have a 1 on it, we can't change/update the email address for you. No matter how many times you change username, the @chess.com email address will always remain the same as it has always been.
I am considering a name change (have not decided yet), but wanted to know what affect this will have on my current chess.com email address. Will my email address change also, i.e. NEW-username @ chess . com OR OLD-username @ chess . com? Also, I assume my login name would change the new name?
Thanks!