One embodiment of the present invention provides a system for transmitting information. During operation, the system receives, by a server from an initial mobile device, a request for transmitting information. The request does not specify a recipient for the information. The system obtains location and/or orientation information associated with the initial mobile device and location and/or orientation information associated with a plurality of mobile devices. The system selects from the plurality of mobile devices a subset of mobile devices based on the location and/or orientation information associated with the initial mobile device and the location and/or orientation information associated with the plurality of mobile devices, and transmits the information to the selected subset of mobile devices.