Who Receives What?
Network-layer Path:
- No expectation of privacy
- May or may not be end-to-end for the underlying communication.
To: and From: information:
- Appears twice – in mail “envelope” protocol and mail header (the two can and do differ).
- May or may not be end-to-end.
- If not end-to-end, what if one ISP is in another country, with stronger privacy guarantees?