How to Block a User from Receiving Messages - Spark

Does anyone know of a way to block a user from receiving room messages? I know you can right click a user and block that user, but that only blocks messages being sent from the user.

The reason I’m asking, is that I’m trying to use Spark to communicate using XMPP with Arista network switches. I have setup several chat rooms for different groupings of users (switches). However, sometimes I’m in a chat room and I want to send messages (commands) to all but maybe one of the users (switches). The current blocking feature will still allow the messages (commands) to go to that one user (switch).