[justlurking]

The sniper might be able to send off email (bounce it off an open relay) but there would be no way for him to receive it without being traced.

This is not correct. I can think of at least two ways to receive a message without being traced. One is fool-proof, while the other is almost impossible within the time it would require to complete.

[lelio]

I can think of at least two ways to receive a message without being traced.
Not with email, but you could do something like post in an IRC chatroom a coded message. It would be pretty hard to trace off of there as you can get onto a foreign computer from here in the US pretty easily. Plus if it is in Super Secret Sniper Code the others in the room wouldn't know what's going on. Hell you could just ROT13 the messages and people wouldn't look twice at it.