Your messages are stored on your own device. If a message cannot be delivered immediately (for example, if you are offline), 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, such as when many people are sharing a popular photo or video, we may retain that content on our servers for a longer period of time.