Hey, My wife has been receiving threatening emails from someone and we know who it is i just need proof... this person is using another email tho.
I know that it can be tracked by IP but I don't know much.
Although I just need some help to proof its this person. thanks!
Be VERY careful when trying to do stuff like that. There's a fine line between investigation and vigilantism. The latter is going to hurt your case, not help it.
The message headers for these emails will show every step the email took in getting to you. The catch to that is that if the person used a Web-based service like Yahoo or Hotmail, the first step is Hotmail or Yahoo, not the sender's PC.
Those sites will be able to use the message ID number in the header to look up the IP address of the computer that was used to create those emails, but sites generally only provide that by subpoena. They have specialized processes for when official law enforcement agencies make the request.