A 21-year-old Armenian calling himself Vahe G has uncovered a way of sending spam to Gmail users. The exploit appears to have been set up for mischief. More malicious hackers could easily have exploited the vulnerability to spread the typical money-making spam or to distribute malware or a phishing attack. Users might be much more likely to click on a link if they saw it really did come from Google, and could put their personal data in the hands of hackers.”]
Source: https://grahamcluley.com/website-exploit-spam-google-com-real-headers/