You can't guarantee a reply unless you FORCE him to read it and lock his inbox until he replies. Who would be stupid enough to run THAT software? LinkedIn has

You can't guarantee a reply unless you FORCE him to read it and lock his inbox until he replies. Who would be stupid enough to run THAT software? LinkedIn has a feature called InMail, that allows you to connect directly with people like Paul Graham, but does not guarantee a response. I've had some success with it, but it does heavily rely on your own ability to craft a cogent message.