The U.S. Postal Service or USPS says it’s illegal to mail materials containing advertising for marijuana products, even in states that have legalized the federally controlled substance. The policy statement released this week comes in response to a letter from Oregon’s Congressional delegation asking the service to clarify its policy on the issue. In November, a memo distributed in the Portland postal district said it was unlawful for newspaper outlets to run marijuana ads and use the U.S. mail for delivery.