I suspect that our server is being slow or you've attached something that's too large for us to receive. Have you tried a simple test email with nothing attached?
Check the address - it should be kobro (at) teleport (dot) com. (And of course don't forget to type in a subject.)
So my best suggestion is to try it again with a simple email. If a simple email correctly addressed comes back to you undelivered, you could try forwarding it to my son's address, which is kopetab (at) whitman (dot) edu.
If one of those comes through, then we can troubleshoot further.