Mail fraud refers to any scheme which attempts to unlawfully obtain money or valuables in which the postal system is used at any point in the commission of a criminal offence. Mail fraud is a legal concept in the United States Code which provides for enhanced penalty of any criminally fraudulent activity if it is determined that the activity involved using the United States Postal Service. As in the case of wire fraud, this statute is often used as a basis for a separate federal prosecution of what would otherwise have been only a violation of a state law.