WhatsApp Tips and Tricks Everyone Should Know
Send a broadcast message
The equivalent of Bccing your message, its cheaper than sending a group SMS. The replies from your broadcast will be visible only to you.
Tap on Menu > New Broadcast, and select all the contacts you would like to round up for the message.
Tap the Broadcast Lists button at the top of the Chats screen, tap New List at the bottom of the screen, filter from your contact list and then tap Create.