A mobile device periodically polls a network server via a communications network to obtain new communications addressed to a client account according to a polling schedule. The mobile device receives an indication of a threshold change of one or more of ambient light, temperature, or proximity of an object to the mobile device via an optical sensor of the mobile device, or an indication of motion of the mobile device via a motion sensor of the mobile device. The polling schedule is advanced responsive to the indication of the threshold change of ambient light, temperature, or proximity, or the indication of motion. The mobile device outputs a notification that new communications have been received by the mobile device from the network server.