However, constitutional rights in the electronic world are largely undetermined. This should not be of overwhelming comfort, though, as one is unlikely to know whether messages have been intercepted or who has been doing the intercepting. Again, situations such as the mailing list example indicate that, in many cases, messages assumed to be private may not be legally protected. The foregoing is just a general summary of one's communication privacy rights. There are numerous exceptions, many of which are quite logical, to these rules.
Intent is also important.
For example, system operators can always forward messages to the intended party or to another party for the purpose of forwarding it to the intended party. This is true even if your worst enemy has tricked the system operator into thinking that he or she is you. Also, the U.S. government can, and does, intercept and monitor messages leaving the United States. Sending a message to an overseas remailer is probably not going to provide anonymity, at least not relative to the U.S. government. If there is an emergency situation involving national security, immediate risk of death or physical harm, or activities likely to be related to organized crime, the U.S. government may be able to intercept messages now and get the warrant later.