The Blacklist is a list of Jarls you don’t want to interact with for any reason.

Blocked Users
Blocking Users
Unblocking Users

Blocking Users

To add a player to the Blacklist, select their name in the Chat and click To the Blacklist in the player menu that appears.

You can also add a player to your Blacklist from the “Mail” window. To do this, select the message of the player in question from the list, then click their userpic, and in the information window that appears click Block.