Can emails be tracked by the computer you sent it from?
Yes. Using the mail header it is easy to track the IP address of the machine from where the email has sent.
There are also more complicated ways that federal agencies use involving satellites to get a more accurate trace, the ones with the headers are completely inaccurate and may even take you to the Internet Service Provider's location.
There is no zip code for emails, since a zip code designates a physical geographical area somewhere in the United States. An email is sent from one computer to a specific email address, accessed on the recipient's computer. The sending computer and the receiving computer can be anywhere, and are not tied to physical locations.