FBI warns billions of Gmail, Outlook, Android, and iPhone users about cyber threats.

The FBI has issued a warning to billions of Gmail, Outlook, Android, and iPhone users to watch out for "money message" red flags that could indicate a Ponzi scheme. The agency has listed seven red flags to look out for, including high returns with little or no risk, overly consistent returns, unregistered investments, unlicensed sellers, secretive and complex strategies, issues with paperwork, and difficulty receiving payments. The FBI advises people to report investment fraud messages to them and the FTC via their respective websites.