Well, yes, it can be turned off and yes it can be not sent, but that's at the discretion of the client. They can "hack their client" to send it anyway which is

Well, yes, it can be turned off and yes it can be not sent, but that's at the discretion of the client. They can "hack their client" to send it anyway which is why everyone has to "refuse" to receive it from a "muted" client, as well. It's a second line of defense. Never trust the client.