A messaging and content sharing platform that allows for sender-controlled permissions and rules. During operation, a sending device can receive user input to set permissions and rules for an object to be sent to a receiving device. The permissions and rules control how the object will be managed after leaving the sending device. A receiving device receives the object and complies with the permissions and rules associated with the object. Other features of the platform include a hierarchical view for group messaging, an attachment-only view of messages, large file attachments, and the ability to allow users to access external services such as social networking websites without logging in.