Quote Originally Posted by Exmo View Post
This doesn't make sense. The blacklist feature blocks another player and their alts. Therefore, the client needs to know some info about those alts so it can block them.
The client doesn't need to know anything in that regard if that stuff is handled on the server. Let's say Player A logs in on an alt to harass Player B. Player B has Player A blacklisted and therefor the server simply would not send the data about Player A to Player B at all. If blacklists would work in both ways then the Player B data would also not reach Player A.

The way it is now the server sends the data all the time and the client has to handle it, with blacklist data that is from the self-same server. The Blacklist is already saved server-side so it should also be handled there instead of sending an immutable ID of everyone that can be linked to everything on their accounts.