[Tutor] Parsing email headers

[Jim]

OS = linux Mint 18,xx

This may be a little OT, as I am as interested in the process leading up 
to parsing the header as I am in the results of parsing it.

What I want to do is figure out where an email came from without 
actually opening it. We all get possible malicious emails. Some are 
obvious but some look pretty real. Many times the From line just says 
"Google" or "Chase", etc.  I wrote a little bare bones script that will 
print out the From:, Return-Path: and the Sender: names from the header.

Right now using Thunderbird, I right-click on the email in question. 
Then I click Save As and give it a name. It is then saved as a .eml 
file. Then I give the file name to my script and see the header info.

I worry about discarding a legitimate email or getting some type 
infection by opening an email to check if it is legitimate. So am I 
protecting myself with the above procedure or will the above procedure 
still subject me to risks of opening a bad email?

Right now it is a fairly manual process. If it is worth while I would 
like to spend the time making it a one click process if possible.

Thanks,  Jim