How to Show Full Headers In Gmail

To get full headers from a message in a Gmail account:

1. In Gmail, open the message of interest.
2. Click on the arrow next to the word "Reply," at the upper left of the message:
   
   
3. Select "Show original".
4. The full headers, plus the text of the message, will appear in a new browser window (or tab, depending on your browser's settings.
5. Right-click anywhere in this window, then click Select All.

Right-click anywhere in the now-highlighted text, and click Copy