The need for upload security arises during content sharing between users in communication link with each other and a server. In one embodiment, providing the upload security involves the server identifying a mobile device that sends an upload message destined to a user. Providing the upload security further involves the server accessing opt-in parameters predetermined by the user, determining if the identity of the sending mobile device is included in the opt-in parameters, and, if so, allowing the upload to the user's account, otherwise blocking the upload. The opt-in parameters include the identity of mobile devices that are authorized by the user to upload data to the user's account. In one embodiment, the communication link includes a wireless carrier network with capability for security screening of the upload message before it reaches the server based on the identity of the wireless carrier network.