Gmail recommends sending the full message header of a spam email to the Federal Trade Commission at [email protected]. Source
However, in order to get the "full header" you need to open the email Source
My question is: can opening the email give me a virus??
The short answer is: Yes.
Using software to interact with untrusted data is inherently risky. There are all kinds of software problems from browser bugs to image processing bugs, and there are very naughty people out there. Once upon a time I made a statement that image files were just data and weren't at all risky w/r/t malicious software. At the time I was right. That was a long time ago.
You've got to balance the risks versus the rewards. Reporting spam to the FTC might be a worthwhile reward to balance the risks involved; I won't tell you it isn't.
The likelihood of being infected by looking at the source of a suspicious email using Google is relatively low, but the possibility exists.
Possibly. Rotating ads on any web page can cause infections, so if the email you receive is in HTML format and has a remotely placed rotating ad that has been compromised, then yes, you can definitely get infected. If you use ad blocking software in your browser, it will usually stop this from happening. But it is of course no guarantee.
If you trust Google to scan and sanatize the mail before allowing it to be displayed in your browser, then go ahead.
If you are really concerned, you can go into Gmail Settings › Forwarding and POP/IMAP, enable POP Download or IMAP, and use a traditional mail client to fetch that particular piece of mail.
