It means what it says, pretty much. There is no network path from your computer to the SMTP server. Perhaps there is a firewall or a router blocking the path, or perhaps your computer is not connected to the network at all. Talk to somebody who understands the network to find out exactly what the problem is.
And now
you should be able to see that the fact that it can connect to the SMTP server from some other computer has nothing much to do with this problem.
Edit: looking at the stack trace, your code is actually trying to send an HTTP request. So it isn't trying to connect to an SMTP server, it's trying to connect to an HTTP server. Same network problem, though. And I don't see any JavaMail classes in the stack trace either. That doesn't change anything about my answer either, it's just harder to identify the problem when you post misleading information.