Is there any way to send a message to my neighbor's PC without them installing any software? I've found ways to do it if we both have the same messaging software installed, but I want to be able to do it without them having to install anything on their end. The reason being my cable modem has croaked and Comcast won't come until Wednesday. So being netless of course I turned to the charity of those that don't secure their shit. I'm not out to do anything malicious (other than stealing your bandwidth and slowing down your connection) but I went through the routine 'router check' and discovered they have their shit wide open. I wanted to inform them without having to do it face to face.