API SendMessage to all devices?

Hello! 

I'm new here. Didn't see any discussions on this topic, but wondering if anyone has found a way to use the SendMessage API (Send a message to a bulk of devices | Dell Wyse Management Suite API | Dell Technologies Developer) to send a message to ALL devices. The documentation states that you have to supply a list of either MAC addresses or serial numbers as message targets. I'm wondering if there is a way to specify all devices or a device group as the target.

Thanks!

Kirk