Hacking Gmails UX With From Fields explains a bug in the way Gmail organizes its folders/filters based on falsifying the From field. Any email so forged automatically enters the recipients Sent folder giving the false impression to the unwitting user it was an email they themselves sent. Google has resolved this issue and issued me a $100 bughunter reward through Google’s Vulnerability Reward Program. Updated 20190116: Added a section showing the Inbox/Sent views with examples and included insight from Hacker News regarding other vulnerabilities.”]
Source: https://blog.cotten.io/hacking-gmail-with-weird-from-fields-d6494254722f