President George W. Bush signed the CAN-SPAM Act on December 16, 2003. The law does not ask a sender for permission before a first commercial email. Instead, each message must explain “how the recipient can opt out.” The sender must honor that request “within 10 business days.” The law “makes no exception for business-to-business email.”
In daily work, this means an American professional may email a stranger to offer a product or service. The law does not require the stranger’s permission first. The stranger can stop the emails by opting out.
Not everyone liked the law. Critics called the law the “You-Can-Spam” Act.