Implementing communication barriers in a group-based communication system is described. In an example, a privacy setting associated with a communication privilege for communicating with a user of a group-based communication system can be stored, wherein the privacy setting permits the user to transmit communications via the group-based communication and restricts another user of the group-based communication system from communicating with the user. The group-based communication system can deny a communication privilege of the other user based at least in part on the privacy setting, wherein denying the communication privilege prohibits the other user from at least one of initiating a message associated with a user identifier of the user or transmitting the message to a client device associated with the user identifier.