Clients are responsible for storing their own customer contacts and messages. WhatsApp does not store this data for any longer than necessary to route and deliver messages. If a message cannot be delivered immediately, we may keep it on our servers for up to 30 days as we try to deliver it. If a message is still undelivered after 30 days, we delete it. To improve performance and deliver media messages more efficiently, we may retain them on our servers for a longer period of time.