Certain scurrilous emails smearing Presidential candidates are circulating. Email is not anonymous. There are ways, ways that don’t require advanced technical knowledge, of tracking down the source of an email. Even in cases where it has been forwarded, it is possible to track down the original source.
In the United States presidential candidates receive Secret Service protection. If your email can be reasonably interpreted as an incitement to assassination, the Secret Service will track you down. They will obtain search warrants, require your Internet service provider to provide your identity, and come knocking on your door.
Do no play this game. None of us are amused.