With the Broadcast List feature you can send a message to several of your friends at once.
Broadcast Lists are saved lists of message recipients that you can repeatedly send broadcast messages to, without having to select them each time.
This will create a new Broadcast List. When you send a message to the Broadcast List, it will send to all recipients in the list. The recipients will receive the message as a normal message. When they reply, it will appear as a normal message in your Chats screen; their reply will not be sent to other recipients in the Broadcast List.
Note: Only contacts who have added you to their address book will receive your broadcast message. If your recipients are not getting your broadcast messages, check to make sure they have added your number to their address book. Broadcast Lists are a one-to-many communication. If you want your recipients to participate in a group conversation, you should create a Group Chat instead.
WhatsApp Support Team