You don't need to be able to decode email headers yourself to find out where a suspect email is coming from. You only need to be able to view the header in your email program. (The process differs among email clients. Check your program's Help section).

Then copy the whole header and go to a site like https://www.iptrackeronline.com/email-header-analysis.php and paste just the header into the analysis box. That site will tell you who is the apparent sender.(The "From" line in the header is often a forgery.)

If you are willing to do a bit more work, you can also help others by forwarding a copy of the complete email to SpamCop.net which will send a copy of the offending email to the Internet Service Provider that was used to send out the Spam. You will need to register at https://www.spamcop.net/anonsignup.shtml Some ISPs will indeed take action against scam emails (though many Spammers will just open accounts under another name--at least it slows them down).

SpamCop can be a bit user unfriendly. There needs to be at least one blank line between the header and the text of the Spam for the decoder to work. If there isn't, you need to put one in.

Alas, the current administration in Washington has elected to shut down its consumer Spam collection email address which used to collect Spam from users to help regulators decide where to target the federal government's very limited Spam enforcement activities. This was very easy to use, though it went after only the really big fish.

Edgar replies: Jon, thanks so much for the very helpful additional information.