Wouldn’t this be more appropriately called “email headers” and not source code?
Source code is text in the syntax of a programming languages than can be compiled or interpreted to run a machine.
That stuff is just data.
How is any of this going to matter, so we track it down to an Italian email address.
The email is dated January 25 which means “Ellie Light” is now fully aware of attempts to identify the origin of these letters. You can mask your IP address or even spoof your IP address pretty easily.
There are a number of sites that allow you to browse anonymously and/or mask your IP.
Of course that assumes the person in question is smart enough to engage in basic self preservation from a privacy standpoint. I wouldn’t at all be surprised if the true address of “Ellie Light” turned out to be 1600 Pennsylvania Avenue or someone in the OEOB.