# WhatsApp Mailing

- "Customer service window" - 24 hours from the moment of receiving the last message from the client.
- If a client starts a WhatsApp conversation, no consent or templates are required within the "Customer service window".
- Messages that you send to the client outside of the "Customer service window", including if you want to write first in WhatsApp, must follow a template (HSM - Highly Structured Message) and the client must provide the consent of such messages in advance.
- Message templates for sending outside of the "Customer service window" are pre-agreed with WhatsApp. Templates approval is free at any tariff. Templates can be with buttons.
- If a customer responds to a template message, a "Customer service window" opens, which does not require templates.