If you are a WhatsApp user, then you know how to send a WhatsApp message to all your contacts at once. This is an easy way to keep everyone in the loop about what is going on with you and make sure that everyone has the latest information. To do this, open up WhatsApp and sign in. Then, go to the Menu bar at the top of the screen and select Settings. Under General, select Message History. Now, under Message History, select All Contacts. This will add all of your contacts to the list of people who have received your WhatsApp message. Now, just send a message to all of your contacts and they will receive it automatically!