In Multichannel, there are three methods to send message to customers.
Please be informed that method number 2 and 3 requires quota that can be purchased from us.
1. The first is ordinary message by text field, that can only be sent within 24 hours after customers’ last message. You will get error "Message failed to send because more than 24 hours have passed since the customer last replied to this number". You can see method number two for the error example.
2. The second way is by using a button called "Send HSM". This will sent a template message that has been submitted before. The button will only appears after 24 hours has passed since customers' last message. You can read further here: Outbound WhatsApp 24 Hours Message Template
3. The third way to send message to customers is by using HSM Broadcast. With this, you can use a submitted template to send messages to hundreds of customers by using CSV containing list of numbers and variables.This kind of message can be sent even to customer that haven’t entered Multichannel yet. For further reading you can read here: Outbound WhatsApp Broadcast Templates