The forgery of an email header so that the email appears to have originated from someone or somewhere other than the actual source. Spammers use spoofing to disguise their identity in an attempt to get recipients to open, and possibly even respond to, their solicitations while avoiding prosecution for sending unsolicited emails. MyNewsletterBuilder (MNB) has a strict anti-spam policy prohibiting you from spoofing in accordance with the CAN-SPAM Act.