Before you may send messages to your customer, he must first consent to receiving WhatsApp messages with an active opt-in. This opt-in must be done via a third-party channel. This can be any channel you already use to communicate with your customer, for example your company website, app, email, SMS, store, etc.
Active opt-in for receiving WhatsApp messages
The opt-in must be an active one. This means the opt-in is done by a user action, for example when the customer enters his phone number or checks a box to give consent to you using his number for WhatsApp messaging. Also, you need to clearly inform the customer on what exactly he is opting in for. So, what type of messages will the customer receive? This doesn’t mean ‘WhatsApp message’, but what type of content you will be sharing.
To make the opt-in requirements a bit clearer, I’ll share the Third-Party Requirements as stated by WhatsApp itself. The opt-in must have a visual element (check box or similar) next to the WhatsApp name + logo. The user should be able to enter or edit the phone number used for opt-in, meaning he has control over what number is used. Also, it must be explained clearly what information will be received and that this will be shared via WhatsApp.Image source: WhatsApp/Facebook
A customer sending a message to a company is therefore strictly not an opt-in. If a customer sends you a message, you may send him replies for the duration of the customer care window. If you want to send notifications, an opt-in is required.