OK, I just try at my server and i think that option do nothing in this problem.
Client who receive that message get an Error: #134 message and close after that, don't know your case is same to me.
The player who send the message will also get a client crash after he send that message.
I have try using whisper, guild, say, yell (I have modify the Player::Yell and my yell is a world chat channel, and the test crash all my player's client.) channel to send that message, and very sure that only player receive that message have a client crash.
This is just a small test and may not accurate or may not your scenario, but I hope this can help you.^^